Pragmatic me thinks: "It's kind of weird that we encode the idea of two adults sharing a home, family, and bed to the exclusion of other models, but IF we're going to do that we should let gay and straight couples do so"
Idealistic me thinks: "Why the hell does the government recognize marriage anyway? People arrange their lives in dozens of different ways. A person can coparent/cohabit/have sex with/share medical choices with/share financial choices with/(etc.) a number of different partners, but we've decided "two adults doing all of those things is the norm, and anything else is less than ideal", which is a bit stifling.
There are other models. Maybe the Mosuo "walking marriage" should become a codified norm instead?
