I'll just say that it seemed like a good idea at the time. My partner’s hetero without the flexible, so our progressive, sex-positive little setup was, of course, inherently unequal, which we felt acutely when we put it into practice. Also, the clause about notifying the other partner before hooking up with someone else? It sort of worked, but if the heads-up doesn’t happen for whatever reason, the sex is a betrayal. And if we were going to expand our arrangement to allow for either of us to get with someone of any gender, we suspected that informing each other in advance could get unbearably awkward. “I just can’t imagine calling you on a Saturday night and saying, ‘Hey babe, I met someone cute at this bar, we’re gonna go to his place,’” I tell my partner. He laughs and agrees.