Claire is a pretty, 31-year-old Park Sloper who studies furniture design. Her husband, Alex, is a 32-year-old Web-design consultant with a fondness for floral shirts. He’s the center of attention at a party; she’s the one off to the side, seemingly aloof but really just shy. That’s why she was shocked when, more than a year into their relationship, she was the one who found herself attracted to someone else.

 

“I was totally confused, because I’d assumed that once I found ‘the one,’ I would be done with all that,” says Claire. “Going through all this was hard for us as a couple.” But when her husband subsequently got a crush of his own, she was more prepared. “Now that it was his turn, I was in a position to understand,” explains Claire. “So I told him, if he wanted to kiss her, that was okay—but I wanted to know about it, and I wanted that to be as far as things went without him talking to me first.”

For much of human history, monogamy (or, at least, presumed monogamy) has been the default setting for long-term love. Hack the system, goes the theory, refuse to forsake all others, open the door even a crack—and the whole relationship will crash. Any dissenters have been pathologized as delusional idealists or worse. But now a new generation of couples is employing a kind of homeopathic hypothesis: that a tiny injection of adventure will ward off the urge to stray further—as long as it’s all on the table and up for discussion. (And just as with homeopathy, a healthy percentage of the population considers this premise bunk.)

“I realized I really didn’t care what he did, I only cared how he felt,” says Claire. “So we spent many hours discussing our expectations and came up with a deal: Anything above the waist is okay, as long as we tell the other person. If it’s a problem, then we have to say so. And we’ll work it out.” So far, these negotiations have remained friendly. “I think the permission alleviates a lot of the stress of being with only one person for the rest of your life and makes us both feel lucky to have such an understanding partner.”

For years, we have said—to each other, to our boyfriends, to people writing in to our advice column—that monogamy is a choice, and if you expect it to come naturally, then your relationship (or your shot at one) is doomed. In other words, don’t take monogamy for granted; take the urge to stray for granted. But then again, our underlying assumption was that of course you’d choose monogamy, because what other choice was there? That’s what happily-ever-after requires. Although we may crave a fling on the side, the thought of our partner’s doing the same is heartbreaking, and so we agree to fidelity in order not to drive each other crazy.

But lately, these questions have become more than just theoretical. Em is engaged; Lo is in for the long haul with her fella. And we each recently began toying with the idea—independently of one another, and well before we were assigned this article—of arranging happy endings for our boyfriends at a Chinatown massage parlor, as a sort of gift in honor of long-term monogamy. Who knows where the idea came from? Was it something in the air? Pure generosity? Or a way to beta-test an idea? And could we go through with it? Probably, if we handled the arrangements, we agreed over a bottle of red one night at a Brooklyn wine bar. Naturally, we imagined the most clinical of hand jobs administered by wizened, grandmotherly ladies. But still, we took it as a sign of the times and of our evolution.

The idea of jimmying the lock on monogamy is not new, of course. Even before marriage made the leap from an institution designed to protect property to something a bit more intimate (and in recent decades, with the changes wrought by feminism, to a freely chosen option for women), early American communes like the Oneida Community, founded in 1848, advocated nonpossessive love and “complex” (i.e., nonexclusive) marriage. In the fifties, Kinsey’s researchers swapped spouses. And by the seventies, the more daring members of the divorce-slash-therapy generation were experimenting with the form: key parties, organized swinger communities, and—inspired by the 1972 book Open Marriage, by George and Nena O’Neill—sanctioned slutting around.

It never quite caught on, though, in part because the prospects of extramarital relationships (or even temptations) were so heavily skewed toward men, who had all the freedoms and fewer erotic prohibitions. These days, however, a woman is as likely as a man to attend a sales conference in Des Moines. E-mail, text messaging, and online porn and personals provide both men and women with privacy and virtual intimacy. Both sexes stay single longer, and variety is built into the way they think of their sex lives. The increasingly open gay community has dramatized the fact that there isn’t just one way to be two. Even evolutionary psychologists, once stalwarts of the men-cheat-women-cling school, are questioning whether females are innately monogamous. Perhaps this time around, seventies-style swinging and slutting will actually be feasible—and fair.

Or maybe people will just start talking about it more. Because in its mildest form, managed monogamy is nothing more than the ability to joke about temptation. Our friend Patrick is fond of introducing his wife, Anne, as “my first wife.” Ty and Lynn tease each other about their respective “work girlfriends and boyfriends.” Andrew and his fiancée, Heidi, browse online ads to stimulate role play—imagining three-ways in a manner that is sheerly theoretical, so far. And then there are the popular celebrity lists swapped between partners, like a dirty game of fantasy football.

“My fiancé and I each have a Hump Island,” says Karen, a 30-year-old editor. The idea being, which stars occupy their personal fantasy retreat? “The island has many iterations,” Karen explains. There’s Geriatric Hump Island (“for Robert Redford and Catherine Deneuve”), Lolita Hump Island (“That was for him, before Natalie Portman turned 18—I didn’t invite any young boys”), and Homo Hump Island (“He’s picked Elvis Costello, though I think it’s more of a man crush than an actual attraction”).

What all these lists have in common is that they’re not meant to be attainable—mutual friends are definitely not welcome on Karen’s Hump Island. And even if she should find herself behind a velvet rope with the Sundance Kid, she’s not supposed to really make a move.

However, not all couples keep the people around them out of the fantasy mix. Some freely scope men and women together—and a few go further. “My ex and I used to go to a bar and see who could start a conversation first,” says Kirk, a 32-year-old film editor. “It never went past flirting, but then we would go home and role-play the scenario. It always made for hot sex but never crossed the line of fantasy.”

Of course, the trick is to keep that line from moving. Which is exactly why neither of us mentioned the happy-ending idea to our boyfriends. Until now.

But let’s face it: Batting around hypotheticals is beginners’ stuff. “Before I met my boyfriend, I enjoyed nasty IMing and phone calls with a stranger I call my insignificant other,” says Diane, 30, a renovations project manager. When the couple got serious, they started negotiating and decided to be monogamous in physical acts only; they are still free to flirt, talk dirty on the phone, and share fantasies over IM. “As long as no one ends up actually making out with anyone else, it’s all fine.”

There are risks involved in such experiments, of course: Letting your partner talk dirty is one thing; reading the transcripts another. So for many, being more directly involved in the dalliances can be, ironically, the more comfortable choice. Take strip clubs. “On my boyfriend’s birthday,” says Melinda Gallagher, Club Cake founder and co-author of A Piece of Cake: Recipes for Female Sexual Pleasure, “I asked all the female Cake dancers to give him a collective lap dance. We are friends with the dancers, so it was cute and playful.” And the giving goes both ways: “I wouldn’t hesitate to get him a lap dance at a strip club, but he usually prefers to get them for me instead.”

If you’re partners in crime, it would seem, then there’s really no crime.

Jonathan, an attorney, and his wife of one year, Natalie, both 30, prefer to keep professionals out of it, but they too like both parties to be present. “We’re more a couple who does everything together than a couple with separate social lives,” says Jonathan, “and that’s not about to change because we’re talking about nookie.” They recently took part in an extended game of Truth or Dare, says Natalie. “It involved a lot of kissing and feeling up—boys on boys, girls on girls, all combinations—and me getting licked navel to throat by the hot 23-year-old girl across the table.”

Mike (42, writer) and Jessica (31, graphic designer) just celebrated their fourth anniversary. “When we first started dating, we talked about monogamy and how it seemed to create more problems than it solved,” says Mike. “So we decided we’d be open to new things, so long as we told each other everything and never did anything for the sake of the experience—we would only have sex when we were actually turned on.” They tested the waters by making out with people at clubs, and then a year or so later, had a three-way with a mutual friend. When that experience didn’t lead to jealousy, they agreed to “being open to other possibilities as they came along,” says Mike. Those “possibilities” have included, to date, make-out parties, more three-ways, a four-way (Jessica had sex with both members of the couple, Mike only with the other woman), and a full-blown orgy. They’ve even had the occasional licit one-night-stand independent of one another.

How free! How . . . polyamorous!

“We’re not polyamorous,” insists Mike—and in fact, every couple we spoke with said the same thing. “We don’t date other people, and we don’t have romantic relationships with our sex partners—though we’ve become close friends with some of them.”

If he sounds a bit defensive, it’s understandable. Because in most people’s imaginations, you’ve got on the one hand your earnest, hairy polyamorists (see San Francisco) and on the other, doughy, middle-aged swingers (see Minnesota or HBO). These are the bogeymen of today’s hipster open relationships—if we swing tonight, can a purple muumuu and a relocation west be far behind?

“What’s new here is not that couples are being nonmonogamous,” says Stephanie Coontz, professor of history and family studies at Evergreen State College in Olympia, Washington, and author of Marriage: A History. “It’s that couples are negotiating the terms of their monogamy.” Of course, such negotiations can be as exhausting as cheating ever was; just ask anyone who’s tried to plan a “nontraditional” wedding. There’s something to be said for the well-worn path—it’s like a built-in referee. Sure, you might not agree with his calls, but at least he always has one.

“My dad’s a Presbyterian minister, so monogamy was always a very black-and-white concept,” says Stacey, a customer-service rep. But then a few years ago, two close family friends got divorced—not because they no longer loved each other but because they were attracted to other people. Stacey had herself been cheated on, so when she met Nate, her husband of more than a year, she told him that if he wanted to hook up with someone else, he should tell her. “I wanted a relationship strong enough for him to share his desires with me, even if those desires weren’t about me. Because what had really hurt in the past was not the indiscretions but that my partners had lied.”

Stacey and Nate married young, at least by New York standards: She was 24 and he 25. And neither of them has acted on their do-ask-do-tell policy. But Stacey finds the agreement a comfort nonetheless. “We know that relationships are always changing,” explains Stacey. “Our marriage means we’re going to stick together through those changes.”

Many straight couples struggling with these issues look to gay male friends, for whom a more fluid notion of commitment is practically the norm. William, a 34-year-old teacher, has been with his boyfriend, Dan, for more than five years. “We are totally closed for now,” insists William—but it’s not what you’re thinking. “It doesn’t rule out me making out with foreign boys against parked cars when Dan’s out of town.” Ah, semantics.

“Talking about my sexual adventures outside my relationship shocks my straight friends, then titillates them,” says William. “Until finally they recognize the permanence of my relationship and begin to reinterpret it all as healthy and evolved.” Exhibit A is William’s married friend Nick, who took notice and took action. “Being a spectator of Will’s easy-come-easy-go escapades, though recognizably self-destructive at times, inspired me to bring some casual lust to a vagina not belonging to my wife,” he explains over e-mail. He was able to finagle a swinging episode with another couple. “I can’t say that my wife and I would never try it again. Her getting off turns me on.”

Never let it be said that these new monogamists don’t know how to articulate their desires. In fact, their loquaciousness goes a long way toward explaining how and why they do it like they do: We’re living in an age of unprecedented emphasis on “communication” in relationships. (Yep, one more thing to blame on your shrink.) Thousands of books detail how couples should communicate their wants/needs/desires/pet peeves to one another. Not happy? Communicate your concerns. Bored with your sex life? Communicate your fantasies. Had an affair? Communicate your fuckup. The result of this communication-bingeing is that negotiation is starting to trump discretion. A man is copping a feel because his partner says he can, not because her back is turned. But he’s still copping a feel.

And then there are the couples who are copping more than a feel. The 33-year-old photographer Clayton James Cubitt (a.k.a. Siege, for C.J.) and his fiancée, Katie James, a 35-year-old makeup artist and photographer, met in Minneapolis in 1999. “I knew immediately that this was the woman I was meant to be with,” says Siege. “The woman I’d been growing toward my whole life, and there’s nothing else I need.” Well . . . almost nothing.

Because their relationship was long-distance, they started off as friends-with-benefits. During late-night calls, they swapped stories about their flings. “We would give each other little assignments,” says Siege. “Like, go off and do this, and send me a picture of it.”

When Siege moved to New York, he knew what he wanted. “I didn’t want to fuck it up,” says Siege, “but I knew I couldn’t do the fidelity thing.” A prior seven-year monogamous relationship had ended when they both cheated. Katie had also recently ended a seven-year relationship when she discovered her boyfriend was fooling around—with both women and men. “It hit me that humans aren’t meant to be with just one person,” she says. “It’s like, you have this best friend, and you want the best for him. So if he’s hot for that chick over there, you want to be like, ‘Yeah, go for it!’ ”

These two are open in every sense of the word: with each other, with everyone they meet, even with the public (Siege has a blog on Nerve.com to which he posts documentation of their escapades). When we requested an interview, Siege invited us to the Williamsburg apartment he shares with Katie. We both hesitated, then Em suggested a coffee shop two doors down instead. We’re usually fearless about nosing into people’s relationships, but knowing that this couple entertains guests on a more intimate basis threw us off balance. “What if they hit on us?” Em asked, insisting that she be the stenographer so Lo could handle the majority of the eye contact. “What if they don’t?” replied Lo.

It’s a response Siege and Katie are familiar with. “If you’re attracted to a friend, it’s like, are you going to skeeve them out?” says Siege. “But if you’re not, are you going to insult them?” Like George C. Scott reportedly once told an actress, “I apologize if I get an erection, and I apologize if I don’t.”

To our pleasant surprise, however, there is absolutely nothing skeevy about Siege and Katie. They’re smart, funny, polite, hip, attractive, self-deprecating, and affectionate with one another. And that’s the most disconcerting thing of all. Call us snobs, but it’s easy to dismiss suburban swingers who show up at orgies with a Tupperware container or Bay Area hippies missing the irony gene. But when a couple like Siege and Katie decry strict monogamy? It makes you wonder, How old-fashioned, socially programmed, and ass-backward am I?

These two can certainly teach most couples a thing or two about communication: They finish each other’s sentences and tease one another gently about the few times they’ve failed to follow their own simple yet strict rules. (1) The Vampire Rule: If they’re both in the same city, they have to make it back by dawn. (2) The Three-Strikes Rule: All pinch hitters must be interested in befriending both Siege and Katie (and vice versa); however, up to three solo dates are acceptable to warm someone up. (3) The Postcards Rule: If they’re seeing someone else on their own, they must bring home photographic evidence. (4) The Woman-Only Rule: Katie is bisexual, Siege is not—thus, for pinch hitters to meet rule No. 2, they must be female. (5) The Veto Rule: for Katie’s benefit, allowing her to rule out potential home-wreckers. (6) The Safety Rule: What some couples call “body-fluid monogamy,” i.e., always use condoms when having sex with a third . . . or a fourth . . . or a fifth . . .

Above and beyond the rules, what makes their relationship work, say Siege and Katie, is that they’re a team, and that comes before anything (hence the Three-Strikes Rule). In fact, this idea of working together came up repeatedly with couples who have tweaked monogamy: Part of the appeal, it seems, is a sort of “us against the world” vibe. More than one couple referred to their additional partners as living, breathing sex toys.

After about an hour of enlightened coffee-shop conversation, even we started coming round to their way of thinking. Now ashamed of our own measly massage-parlor schemes, we started seeing ourselves as sexual Neanderthals introduced to the advanced civilization of lust. But then Katie said something that jolted us out of our daydreams:

“Sometimes we’ll go for months when it’s just the two of us. But if I just happen to be busy or not in the mood, then I’m not going to stop him. For example, the other night I had a bunch of work to do, so when Siege brought a new girl home, I stayed in the bedroom while they took a bath. I walked past and just said hi.”

Em typed away without skipping a beat and Lo nodded professionally, as if to say, “Ah, yes, you simply popped your head in politely, as one is wont to do when one finds one’s boyfriend screwing a total stranger in one’s bathtub.” What?! We kicked each other under the table—our previously worked-out, intricate signal for “Holy crap!” We were no longer wondering whether we got it; we now knew for sure. We didn’t. No matter how appealing the spokespeople, there are some things that will just never compute for your average (i.e., occasionally insecure or jealous) couple. There is no way not to admire Siege and Katie, but there is an otherworldly quality to their relationship—talking to them brings on a slight feeling of disconnect, not unlike walking into your local bar and spotting a celebrity.

If Katie and Siege have taken their nonmonogamy to the extreme, perhaps it’s because they fit a pattern we saw emerge in our research: The most smooth-running nontraditional relationships, it seems, comprise a straight man and a bisexual woman who’s not particularly interested in men besides her No. 1 guy. “I wish I were bi,” says Siege. “It’d make things easier. But it’s like this island of old-fashionedness in my brain—I just don’t want her messing around with other guys. Because I don’t find men attractive, my only instinct would be to punch them.”

In fact, it’s rare to find hetero couples where the guy is willing to entertain even fantasies involving other men. Christen, a 33-year-old performance artist, says that neither she nor her husband are “conventionally straight,” so they ogle men and women together—like “pretty boy Mig from Rock Star: INXS.” But we found that male-female couples like this are few and far between.

It’s impossible to isolate a single explanation, but we’ll take a shot: Maybe women really are more sexually fluid than men—or their sexuality is simply more socially malleable. Or maybe this is just a particular brand of bisexuality; most of the women we spoke with said they are sexually, but not romantically, attracted to other women. And maybe this is a good thing, a sign that girls have more options, more pleasure, more of an experimental nature, more freedom overall. Or there’s the negative interpretation: Perhaps this is all a performance to turn guys on, Girls Gone Wild Gone Nonmonogamous. It could be that sexually speaking, women are just not taken seriously: Hot, yes, but as sex toys, not real romantic threats. (Who could trump the mighty penis?) As two women about to embark on what we hope will be lifelong commitments, we’re left wondering: Has the bar suddenly been raised? Is female bisexuality the latest way to be the perfect girlfriend?

Which is not to say that women don’t also crave a variety of male partners: “A woman needs to feel potent, too,” says Mia, a 32-year-old CFO. “She needs to know men want her. It fuels her fantasies. It makes her feel alive.” The problem is, it’s rare to find a man willing to negotiate these options. Thus, a hetero woman is more likely to be nonmonogamous in a don’t-ask-don’t-tell set-up such as the 50-Mile Rule (don’t sleep with anyone who lives in your city) or to simply cheat. “Before Tom and I were engaged,” says Mia, “I could leave town and end up in bed with an entire soccer team and he’d never know. And he was always smart enough not to ask.” But once they got engaged, Mia reined it in, figuring they had an unspoken agreement that marriage meant monogamy. Still, her urges lingered. “I did consider fooling around for one last hurrah before I tied the knot, but, alas, a good opportunity never presented itself.”

When partners reject the cult of communication this way, the built-in dishonesty can wreck things right off. “My last boyfriend said he didn’t want to take away my freedom, so I could fuck around so long as it wasn’t with his friends and we didn’t talk about it,” says Sarah, a 26-year-old proofreader. “But he’s a musician, very good-looking and charismatic, and always on tour: He was just protecting his own freedom.” Sarah engaged in her own extracurricular activities, more than she thinks he expected. “I wished we could have been an ethically nonmonogamous couple, but how could I present myself to other guys as an ethical slut when our policy was ‘don’t ask, don’t tell’? I wanted to talk to him about the guys, and I wanted to know what he was doing on tour, but he wouldn’t go there.” They soon split up.

These types of conundrums don’t affect only straight couples. When lesbians Gillian (32, producer) and Kiki (28, psychiatric social worker) met three years ago, Gillian, like many people considering an open relationship, was getting over a cheating ex. Gillian suggested nonmonogamy, and though Kiki was shocked and slightly offended at first, she acquiesced. “I figured that this way, I would get honesty,” says Gillian. But a year in, Kiki hit it off with Susan, a woman with whom they’d had a three-way. Kiki fell in love with the pinch hitter, and the two dated monogamously for a year until Kiki cheated again . . . with Gillian, her ex.

Now Kiki’s got a brand-new serious girlfriend, and they are contemplating a three-way: “We’re going to pick someone that neither of us thinks we could wind up falling in love with,” says Kiki. “Someone a little bit slutty who won’t get attached to us.” Meanwhile, Gillian is single and is done with any kind of open relationship. “I’ve learned that I’m strictly a one-woman woman.”

A similar split comes up in a new documentary out this month in New York called Three of Hearts: A Postmodern Family, about a “trinogamous” threesome comprising two men—Sam and Steven—and one straight woman, Samantha. Living in the city, they marry (well, two marry, all three have a commitment ceremony), they sleep and have sex with each other in one bed, and they have two children—one by each man—over the course of their eight-year relationship. But like many attempted Utopias—which is what any form of monogamy could be considered—it falls apart when Steven declares that he’s not happy and can’t live a life that he feels was always Sam’s idea.

It’s way too soon to tell if managed monogamy is any more effective than its stringent cousin at keeping couples happy for the long haul. Even if people can do it, that doesn’t guarantee them eternal love: Is the open relationship really about freedom, or is it about competition, wishful thinking, controlling cheating, rebelliousness for the sake of being different, or passive-aggressive punishment?

But then, the same could be said of monogamy, which can derive from equally suspect motives. Maybe it’s not sex that makes or breaks a couple, after all; maybe it’s the couple’s willingness to change their minds about what fidelity means. We met many strictly monogamous couples who have no interest in any kind of openness, ever—a high proportion refused to even discuss the subject, with their partner or us. But, remarkably, we didn’t find a single open (or openish) couple who weren’t amenable to being (more) monogamous in the future. “An open relationship doesn’t just mean you’re open to sex with other people,” says Siege. “It means you’re open to changes in the relationship, too.” Over and over, couples told us that their goal is less about sex than it is about wanting a relationship that will bend with pressure, rather than break. “It’s like being held together with an elastic band instead of a ball and chain,” says Bob, a 50-year-old married animation director open to the notion of sanctioned affairs.

Seven years ago, when we were in our twenties, single, and working at Nerve.com, we would proofread sex memoirist Lisa Carver’s diaries and gasp at how “out there” she was, making out with a girlfriend at a party and then calling her husband to tell him how it went. For us and our imaginary future husbands, it was out of the question. We were knee-jerk monogamists who had never been in, or witnessed, an open relationship that worked. Now, with real-life future husbands and decades of monogamy stretched out before us, Lisa’s stunt is neither particularly shocking nor out of the question.

For years, we’ve joked that all sex advice really boils down to is “communicate, communicate, communicate.” Meeting the nonmonogamists did confirm this, in a way—because when, during the course of writing this article, we finally fessed up to our partners about the massage-parlor idea, we realized that doing so was the beginning of a long conversation, about what it means to be together, about variety, about the way we see sex now. (And, as it turned out, Em’s fiancé wasn’t even particularly interested in the idea, especially once it came with a permission slip.) For us—and for many of the couples we spoke with—all this talk about nonmonogamy is, essentially, talk about monogamy. It’s certainly a lot more challenging than learning a new position in bed.

These conversations are far from innocuous, however. What happens if one partner wants to fantasize about a three-way, and the other wants to have one, next weekend, with the hot bassist next door? Once you’ve jointly questioned the conventional wisdom and then balk, it’s not society saying no to the candy—it’s you. The most well-adjusted nonmonogamists we found were those who could acknowledge that what they’re both comfortable with today may freak out either of them tomorrow.

As for us, we’re still monogamists at heart, for now, though we’ve learned not to take that for granted—because we discovered that despite all our preaching, we had, in fact, been taking monogamy for granted. And we think we’ve learned to stop poking fun at all those crazy swingers, too. After all, there’s more than one way to a happy ending.

Managed Monogamy
Above-the-waist rule
An agreement that any touching above the beltline is fair game.
Body-fluid monogamy
When a couple forgoes the latex with each other but requires it for all outside sexual activity.
Celebrity trading card
As seen on Friends: an imaginary laminated card in your wallet—proof that your partner has given permission for you to sleep with the stars listed.
Cheating
Secret, extracurricular romantic and/or sexual activity that breaks the rules. So nineties, so lame.
Closed relationship
How some people in open relationships refer to “old-fashioned” monogamy.
Don’t ask, don’t tell
A policy whereby people in a committed relationship may screw around, so long as they are discreet.
Ethical slut
A promiscuous person who strives to approach partners with respect and honesty. (From the 1997 how-to book by Dossie Easton and Catherine A. Liszt.)
Fifty-mile rule
You don’t sleep with anyone who lives in your city. (Also the title of a 2002 book by Judith Brandt.)
Make-out party
Events open to the public where semi-nudity and above-the-waist fondling are encouraged.
Open flirting policy
An understanding that flirting is healthy, harmless fun.
Open relationship
A long-term, committed relationship in which the couple explicitly agrees to extracurricular sexual activity, either together or individually.
Party bisexual
A woman or a man who engages in same-sex sex-play after multiple martinis.
Pinch hitter
Someone a couple brings in to spice up their love life, e.g., to watch them have sex or to get together with one-half of the couple while the partner watches.
Physical monogamy
You can look, fantasize, and engage in dirty talk— but no touching.
Polyamory
A philosophy of being involved with multiple long-term, intimate partners.
Polyfidelity
Having more than one long-term partner but being closed to additions, e.g. trinogamy (see below).
Polygamy
Multiple spouses.
Swinging
Partner-swapping. Sometimes referred to as “the Lifestyle.”
Trinogamous
To be in a committed threesome.
Work boyfriend/girlfriend
A colleague —your lunchmate, IM partner, smoking buddy, etc. No sex, though.