Consensual Non-Monogamy: Meaning, Types and How Common It Is

By the Rope & Candy team · · Ethical Non-Monogamy

Consensual non-monogamy, or CNM, describes any relationship in which partners openly agree that one or both of them may have other sexual or romantic partners. It includes swinging, open relationships and polyamory, and its defining feature is that everyone involved knows and agrees. It is more common than many people assume: a 2017 study by Haupert and colleagues found that about one in five single US adults had been in a consensually non-monogamous relationship at some point.

If you have seen the term in an article or a dating profile and wondered what exactly it covers, here is the plain version.

What the term means

Break it into its parts. Monogamy is one partner at a time. Non-monogamy is more than one. Consensual is the part that matters most: the arrangement is known about and agreed to, not hidden.

That is the whole difference between consensual non-monogamy and an affair. The number of people might be the same. The honesty is not.

You will often see CNM next to a close cousin, ENM, which stands for ethical non-monogamy. Researchers tend to prefer "consensual" because it describes what is happening without making a moral claim. In everyday speech, people use the two almost interchangeably. Our plain guide to ethical non-monogamy looks at the values side in more detail.

The main types

CNM is an umbrella. The most common forms are:

  • Swinging. Couples enjoying sexual experiences with other couples or single people, usually together, with romance kept inside the couple.
  • Open relationships. One or both partners may have sex with others, often with limits on emotional involvement.
  • Polyamory. More than one loving relationship at a time, with everyone's knowledge.
  • Monogamish. Mostly monogamous with agreed exceptions. Our piece on monogamish explains why so many couples like it.
  • Solo polyamory. Several relationships, no primary couple at the centre.
  • Relationship anarchy. No built-in ranking of relationships at all; each connection is shaped by the people in it.

The edges between these are soft. A couple might swing on holiday, be monogamish at home, and slowly drift toward polyamory over ten years. For a closer look at each one, read types of non-monogamy, explained.

How common is it?

The best known figure comes from the Haupert study mentioned above: about one in five single adults in the US reported having been in a consensually non-monogamous relationship at some point in their lives. It is worth reading that carefully:

  • It is a lifetime figure. Far fewer people are in such a relationship at any one moment.
  • It describes single adults in the US. It is not a number for every country.
  • "Had been in" includes people who tried it once and went back to monogamy.

Large surveys like this are rarer for Canada, the UK and the rest of Europe, so we will not pretend to give you a number for them. What is clear is that consensual non-monogamy is not confined to one country, one age group or one kind of person, on either side of the Atlantic.

On happiness, research by Conley and colleagues has reported similar relationship satisfaction among people in consensually non-monogamous and monogamous relationships. For a wider view of the evidence and what real couples say, see can open relationships work.

"Consensual" can sound like a box you tick once. In real life it is ongoing, and it has a few features worth knowing:

  1. Informed. People know the basic shape of things. A new partner knows there is a spouse at home.
  2. Freely given. A yes given out of fear of being left is not a real yes.
  3. Specific. Agreeing to a kiss at a party is not agreeing to a weekend away.
  4. Revisable. Anyone can slow down or stop, at any time, without having to win an argument first.

Take Claire and David. Early on, they agreed to same-room play only. A year later, David asked about separate dates. Claire was not ready, and said so. They kept the old agreement and revisited it six months later. That pause is CNM working as intended, not failing.

A simple way to keep consent real is a regular check-in:

"Is everything we agreed still feeling okay for you? Is there anything you want to change, add or take away?"

This is general information, not legal advice. In the US, Canada, the UK and the EU, relationships between consenting adults are legal. What is illegal is bigamy, meaning marrying more than one person. A few places have gone further in recognising multi-partner families: Somerville and Cambridge in Massachusetts recognised multi-partner domestic partnerships in 2020 and 2021. Our article is polyamory legal covers the details.

Socially, attitudes vary a great deal from city to city and family to family. Many people in CNM relationships are open with close friends and discreet everywhere else, which is entirely their choice.

Common myths

  • "It's just cheating with extra steps." Cheating breaks an agreement. CNM keeps one.
  • "Those relationships never last." Some do not, and some last decades, the same as monogamous ones.
  • "It's only for young people." Many people come to it in their 40s, 50s and later, once children are older and they know themselves better.
  • "It means anything goes." Most CNM couples have more explicit rules than their monogamous friends.

If you are curious

Start with reading and long, unhurried conversations, then small steps. Talk about what draws each of you, what scares each of you, and what you would want to protect no matter what. Agree on how you will check in, and how either of you can call a pause without a fight. None of this has to happen in one evening, and the couples who take their time usually enjoy the start far more. Our guide on how to open a relationship lays out a sensible order. And if you would like to meet people who already live this way, gently and over a coffee first, you can join Rope & Candy, a free, invite-only community of couples and single women. No tickets, no club, just friends.

Questions people ask

What is consensual non-monogamy?

Consensual non-monogamy, or CNM, is any relationship where partners openly agree that one or both may have other sexual or romantic partners. Swinging, open relationships and polyamory are all forms of it. The key is that everyone involved knows and agrees.

How common is consensual non-monogamy?

A 2017 study by Haupert and colleagues found that about one in five single adults in the US had been in a consensually non-monogamous relationship at some point. That is a lifetime figure, so far fewer are in one at any given moment.

Is consensual non-monogamy the same as ethical non-monogamy?

Nearly. Researchers tend to say consensual non-monogamy because it describes agreement without passing judgement, while ethical non-monogamy is the more common everyday term. Most people use them interchangeably.

Are people in CNM relationships less happy?

Research by Conley and colleagues has reported similar relationship satisfaction among people in consensually non-monogamous and monogamous relationships. Like any relationship, how happy it is depends far more on honesty and care than on the shape.