At the same time, there is some truth to the conservative claim that gay marriage is changing, not just expanding, marriage. According to a 2013 study, about half of gay marriages surveyed (admittedly, the study was conducted in San Francisco) were not strictly monogamous.

This fact is well-known in the gay community—indeed, we assume it’s more like three-quarters. But it’s been fascinating to see how my straight friends react to it. Some feel they’ve been duped: They were fighting for marriage equality, not marriage redefinition. Others feel downright envious, as if gays are getting a better deal, one that wouldn’t work for straight couples. Maybe they’re right; women are from Venus, after all. Right?…

What would happen if gay non-monogamy—and I’ll include writer Dan Savage’s “monogamish” model, which involves extramarital sex once a year or so—actually starts to spread to straight people? Would open marriages, ’70s swinger parties, and perhaps even another era’s “arrangements” and “understandings” become more prevalent? Is non-monogamy one of the things same-sex marriage can teach straight ones, along with egalitarian chores and matching towel sets?