The Torah doesn’t say anything about gay marriage. The Torah assurs and condemns certain activities that gays do. But I don’t understand why we can’t treat gays in our communities simply as people who have a strong ta’aveh that most of us don’t have, and who give in to this ta’aveh.
So the same arguments can be made for those who would be unfaithful to their spouses. And further down the slippery slope (actually not necessarily further down), there would be tolerance for bestiality, incest and child molestation. After all, they’re just giving in to their tayvos.
(Of course, as I’ve said many times, one who has the tayva and does not give in to it will be getting a portion of olam haba that makes me jealous. But the fact that there are people who feel that way doesn’t mean we have to bend over backwards to accommodate twisted marriage.)