What percentage of couples are in open relationships?

Research tells us that about 4 to 5 percent of heterosexual couples have agreed to have an open relationship. In other words, theyve given their consent to not be monogamous. That may seem like a relatively small and, given the stigma surrounding open relationships, unsurprising number.

How common are open marriages?

Around 4% to 9% of American adults engage in some sort of open relationship. In a study of 2,270 respondents, 4% reported being in an open relationship.