Rarely a month passes now without a mainstream publication running a piece on the rise of polyamory, citing statistics that feel simultaneously precise and uncertain. Approximately 4-5% of the US population currently practises ethical non-monogamy. Around one in nine adults has engaged in CNM at some point. These numbers come from real surveys, but what they actually tell us — and what they don't — is worth examining before they become received wisdom.

What the statistics actually measure

Most CNM prevalence data comes from online surveys with self-selected respondents, which means they're measuring people willing to identify themselves as CNM practitioners in a research context. As the stigma around CNM decreases and the vocabulary becomes more widely shared, more people who were previously practising informally become countable. This isn't the same as growth in practice; it's growth in legibility.

The 1-in-9 figure is particularly telling. Having "engaged in CNM at some point" includes a lot of different things: a brief open relationship that closed years ago, a period of swinging that stopped, a short-lived triad that fell apart. It describes lifetime exposure, not current practice. The 4-5% current practice figure, if roughly accurate, represents a meaningful share of the adult population — but it's been relatively stable across multiple surveys rather than showing sharp recent growth.

What seems to actually be increasing

What does appear to be genuinely growing is awareness, vocabulary, and willingness to consider CNM seriously. A therapist in 2016 seeing clients discuss open relationships as a real option was an outlier. A therapist in 2026 who hasn't had at least a handful of CNM-adjacent conversations in recent months is unusual. This reflects something real — but it's closer to a cultural shift in what's speakable than a sharp increase in who's practising.

The vocabulary has spread much faster than the practice. Terms like polyamory, NRE, metamour, and compersion now appear in mainstream features and therapists' office brochures. People who would have had no framework for what they were feeling or doing ten years ago now have language for it. This makes CNM more accessible as a choice, which presumably does contribute to some real growth — but the headline number of practitioners hasn't changed dramatically.

Younger generations and declining marriage

Among younger adults, particularly those in their 20s and early 30s, there is something that looks like genuine increased interest. Marriage rates have been declining steadily, the average age of first marriage continues to rise, and long-term monogamous couplehood as the default life structure is markedly less assumed than it was for previous generations. CNM is one of several alternative structures that become more available when monogamous marriage stops being automatically presumed.

Whether this represents a stable shift or a generational phase that changes as people age is genuinely unknown. There isn't longitudinal data on whether people who explore CNM in their 20s continue practising it through their 30s and 40s at higher rates than previous generations did. The honest answer is we don't know yet.

Why the "on the rise" framing matters

The narrative of CNM being on the rise serves different interests for different people. For media, it's a compelling angle. For practitioners, it can feel validating — the sense that you're part of something growing rather than marginal. For opponents, it's evidence of social decay.

None of these uses require the claim to be precisely accurate. What matters for people actually navigating CNM is less whether the numbers are going up and more whether the social infrastructure — therapists, community spaces, legal understanding, cultural legibility — is improving. On those dimensions, the trend is clearly positive, regardless of whether the practice itself is becoming more common.