What is an open marriage? Open marriage vs. affair

What is an open marriage? A marriage where both spouses openly agree that one or both of them can have sex, and sometimes relationships, with other people. That agreement is what separates it from an affair.

An affair and an open marriage can look identical from the outside: a married person, a dating profile, a second bed. The difference is one conversation. In an affair, your spouse doesn't know. In an open marriage, they do, and they agreed to it. Everything else in this guide, the vocabulary, the rules, the apps, follows from that.

We run a site about discreet dating, so we are not here to lecture anyone. People cheat, and plenty of them have reasons that make sense to them. But if you are married and want sex or romance with someone else, it is worth knowing that there is a second route, that more people take it than you might think, and that the research on how it turns out is more encouraging than the jokes about it suggest.

Open marriage, swinging and polyamory: what's the difference?

Consensual non-monogamy (CNM), also called ethical non-monogamy (ENM), is the umbrella term researchers and the community use for any relationship where the people involved openly agree that sex or romance with others is allowed. Under that umbrella, three arrangements come up most often:

• Open relationship or open marriage: a couple stays each other's primary partner but agrees that either or both can have sex with other people. Usually the outside connections are meant to stay sexual or casual rather than romantic.
• Swinging: a couple has sex with other people together or in the same place, often other couples, at parties, clubs or private meetups. It is social and recreational.
• Polyamory: having, or being open to, more than one loving relationship at a time, with everyone's knowledge. Where open marriage is mostly about sex, polyamory is mostly about relationships.

There are many variants ("monogamish" couples who allow the occasional threesome, "don't ask, don't tell" arrangements, hierarchies with primary and secondary partners), and couples change category over time. The labels matter less than whether both of you know what you agreed to.

How common are open marriages?

About one in ten Americans says they have had sex outside a relationship with their partner's consent; about one in five single adults has been in some form of consensual non-monogamy.

More common than most people assume, though the best-known number needs some care. A pair of national surveys published in the Journal of Sex & Marital Therapy (Haupert and colleagues, Kinsey Institute) found that about one in five single American adults, 21.9% in one sample and 21.2% in the other, had been in a consensually non-monogamous relationship at some point in their lives. A later paper from the same research group in Frontiers in Psychology (2021, 3,438 single adults) found 10.7% had practiced polyamory specifically and 16.8% said they would like to.

Two caveats. Both studies sampled single people only, through Match's annual Singles in America survey, which the authors disclose. And as a critique from the Institute for Family Studies points out, "open sexual relationship" can cover a lot, including casual dating while seeing several people. The same piece cites a 2018 YouGov survey for Brigham Young University's Wheatley Institution in which 12% of respondents had ever had an open sexual relationship.

General-population polls land in the same range. In a February 2023 YouGov poll of 1,000 US adults, 12% said they had had sexual activity with someone else with their partner's consent, and 34% described their ideal relationship as something other than complete monogamy. A 2025 YouGov poll found 11% had done so with consent, 9% had been in an open or polyamorous relationship, and 14% would definitely or probably consider one.

Is cheating more common than open marriage?

Non-consensual non-monogamy is still the more common kind. In that same 2025 YouGov poll, 25% of Americans said they had had sexual activity with someone else without their partner's consent (29% of men, 21% of women), against 11% with consent. Among married people specifically, the Institute for Family Studies' analysis of the General Social Survey found 20% of men and 13% of women reported having had sex with someone other than their spouse while married. Put simply: for every American who has had outside sex with a partner's blessing, more than two have done it behind their partner's back.

Do open marriages work?

Some do and some don't: research finds well-being and relationship quality broadly similar to monogamy, though not uniformly, and clearly safer sexual health than secret cheating.

The worry most people have is that opening a marriage is a slow way of ending it. The evidence does not show that clearly. A review of about four decades of research by Rubel and Bogaert in The Journal of Sex Research found that people in consensually non-monogamous relationships generally reported psychological well-being and relationship quality similar to monogamous people, while noting that much of the research relies on small, self-selected samples.

A US nationally representative survey, the 2012 National Survey of Sexual Health and Behavior, gives a less rosy and probably more honest picture. In the analysis by Levine and colleagues in Archives of Sexual Behavior (2018), people in open relationships reported somewhat lower happiness and sexual satisfaction with their primary partner than monogamous people. That gap was smaller than, though not statistically different from, the gap for people whose relationships involved cheating. We read that as: opening a relationship doesn't fix an unhappy one, and the couples who do it are not all thriving. It is not evidence that it ruins good ones.

The health gap between open and secret

Here the data are clearer. In a 2012 study in The Journal of Sexual Medicine (Conley and colleagues, 1,647 respondents), people who cheated on a monogamous partner used condoms 27% less often for vaginal sex and 35% less often for anal sex than people in negotiated open relationships, and were 64% more likely to have used drugs or alcohol during the encounter. The researchers concluded that secretly unfaithful partners pose a greater STI risk than openly non-monogamous ones. That makes sense: if nobody knows you have other partners, nobody insists on testing, and you are not about to buy condoms on the joint card. The Levine study also found people in open relationships reported more condom use for anal sex than monogamous people did.

Open marriage vs. affair: where is the line?

Consent is the whole difference, and it has to be real consent: informed, ongoing and given without pressure. A few things that are not consent:

• A spouse who "would probably be fine with it" but was never asked.
• An agreement extracted as the alternative to divorce. That's an ultimatum, and resentment is the predictable result.
• Agreeing to an open marriage and then quietly breaking its rules. Many people in open relationships will tell you that cheating within an open relationship is still cheating.

An affair also isn't automatically the worse choice for everyone. Some people are in marriages where the conversation is genuinely impossible, or where the spouse has said no and the person has decided to stay anyway. If that's you, read our guide to staying private on affair sites and what the law says about affairs, because the risks are concrete: exposure, money in a divorce, and in a handful of states a lawsuit against your affair partner. What you lose by going secret is the safety net: no shared rules, no honest testing conversation, and no way back to the truth that doesn't involve a confession.

How to start an open marriage

1. Have the conversation before the profile

The worst way to raise an open marriage is to be caught on an app and propose it as a solution. The second worst is to raise it in the middle of a fight. Pick a calm moment, say what you want and why, and make it clear that "no" is an acceptable answer. Talk about what you hope it adds rather than what your spouse is failing to provide. Expect it to take several conversations over weeks, not one evening.

2. Write the agreement down

Couples who make it work tend to be specific. Things to decide out loud:

• Scope: sex only, or dating and feelings too? One night, or ongoing partners? Together (swinging, threesomes) or separately?
• Off-limits people: friends, coworkers, exes, anyone in your social circle or your town.
• Information: do you want to know everything, headlines only, or nothing? Do you tell each other before or after?
• Places and time: your home, your bed, nights away, holidays and anniversaries.
• Safer sex: condoms with everyone else, testing intervals, and what happens if a condom breaks.
• A veto and a pause: can either of you call a stop, and how fast does it take effect?
• A review date: agree to revisit in a month or three, when you both have real experience to talk about.

3. Sort out sexual health

The CDC's STI prevention advice is short: use condoms correctly every time, get tested and share results with partners, and get vaccinated against hepatitis B and HPV where your doctor recommends it. Its testing guidance recommends yearly gonorrhea and chlamydia tests for women 25 and over with new or multiple partners, HIV testing for everyone 13 to 64 at least once, and more frequent testing (every three to six months) for men who have sex with men who have multiple partners. Tell the clinician you have more than one partner; it changes which tests are worth running, including throat and rectal swabs.

4. Start smaller than you think

Many couples begin with something they do together, or with one partner dating while the other watches how it feels, before both go out. Jealousy is normal and not a sign of failure. What matters is whether you can talk about it without it turning into an accusation.

Best apps for open marriages

Mainstream apps mostly assume you are single, and putting "in an open marriage" on Tinder gets mixed results. Two apps take it seriously:

• Feeld was built for couples and singles exploring non-monogamy and kink. In June 2024 it launched Constellation, which lets you link your profile to up to five partners and label each relationship, so a match can see your spouse is in the picture. Read our Feeld review.
• OkCupid lets you mark your profile as non-monogamous; according to its help center, you then see only people who are non-monogamous or open to it. OkCupid added partner linking in 2016 for users who list themselves as seeing someone, married or in an open relationship, and at the time said only 44% of its users were looking for monogamy only, according to Refinery29's report. See our OkCupid review.

Affair sites such as Ashley Madison and Victoria Milan also have members in open marriages, and some people prefer them because everyone there is already married and expects discretion. Their histories with fake profiles are worth knowing first: see how affair sites use fake profiles.

Honesty with the people you meet

Say you're married and that it's open in your profile or your first message, not on the third date. Single people are entitled to know they're dating someone with a spouse, and in practice the people who are fine with it are the ones you want. If your spouse isn't comfortable with you showing your face, say why rather than hiding it without explanation.

When to get help

A therapist is worth it if the conversation keeps going badly, if one of you is agreeing reluctantly, or if you are opening up after an affair was discovered (a common route, and a hard one). Not every therapist is comfortable with non-monogamy, so ask directly at the first session. Two places to start: the American Association for Marriage and Family Therapy's therapist locator, and the Kink and Polyamory Aware Professionals directory run by the National Coalition for Sexual Freedom, which notes that it does not screen or endorse the professionals listed.

The short version

• Open marriage, swinging and polyamory are all consensual non-monogamy; an affair is non-consensual. Consent is the line.
• Roughly one in ten Americans says they have had sex outside a relationship with their partner's consent; about twice as many say they have done it without.
• Research finds open relationships are not reliably worse for well-being, and safer for sexual health than cheating.
• Talk first, agree specifics, write them down, test regularly, and review together.
• Use apps that show your status (Feeld, OkCupid), and tell matches you're married.