The research I've seen says that infidelity is a huge hot-button issue with overwhelmingly Americans thinking it's about the worst thing you can do (even though divorce and cheating are both at high levels). But I agree with you, ethical non-monogamy isn't cheating, it's consensual de-coupling of sex from commitment. If both partners have chosen that as a part of their relationship style, why does anyone else get any say in it, and why are some people who ought to support that because it applies to them too vis-a-vis traditional marriage so up in arms about some people choosing to do that?

Jim has said in the past that some gay men want to present a very traditional Norman Rockwell kind of married life (just with Adam and Steve) as a way to counter narratives about gays being depraved, etc. I wonder if this isn't just more of the same? Peraps these women want to say, "Hey, we're just like you, except same-sex" and anything that detracts from that (like ethical non-monogamy) feels like a threat to the rights they have won to be seen as having valid marriages/relationships.

It's a theory, anyway...