I fail to see why I would want to in the first place.
If you marry the right person you get an extra shop to sell to, occasional free septims and a food item that makes stamina, magica, and health regen 25% faster once a day. Oh, and they constantly get in your way in whatever home you store them in.
I don’t think it’s even about that, they’re angry because the want to be angry. The why doesn’t matter, if the current right wing outrage du-jour had been… I dunno, left handed people rather than trans people, you’d see all the same people working themselves into a screaming tantrum if a game or movie had a left handed person in it.