More Words, Deeper Hole

Yeah, the thing about same-sex marriage is that, once marriage is assumed to be a union between two partners with comparable rights, enabling it is legally very simple; you just remove references to the sex of the participants. Increase the number, so that people don't have at most one spouse, and lots of things have to be fiddled with, many of them involving money and property: taxes, inheritance, automatic insurance beneficiaries, etc. In many cases the necessary legal hacks and limits on the practice will not please everyone.

But this isn't any kind of moral objection, it's just that an observation that there's much more work involved.