First of all, This is a terrible Idea, if only because players will genocide all the straight dwarves to prevent babies.
With that out of the way, Dwarven society is both quite homogenous, and quite liberal, according to Toady. They are thet are quite close to modern-esque ethics, ecluding (or including?) the genocide. I really don't see any scorn or homophobia happening. They are perfectly content with Elves who reject crappy short jokes and consuming the flesh of a sentient, and goblins who reject general dickery.
That said, It really doesn't strike me as somethign that should be largely relevant to the Overseer. So what, you're gay, good for you. Unless the Overseer is watching a particular dwarf for marriages, it really should never even be important.
Besides, the current system of marriages and friends and such are a little odd anyway. Perhaps a level of strength could be assigned, so that, say, a friend who've you've always known would be more important then a friend you made yesterday who was just eaten. It could include the homosexuals in certain manners, like allowing a secret value for relationships that are more then just "friends". Of course, I should be using Plato's definition of Friends here, under which level 1 is a relationship of utility, or base attraction, or something similar, i.e. dating, or being friends with the woodcutter when you are a woodworker. Level 2 being a signifacantly different one were you feel for them and try to help them, i.e. being genuine friends, sorta closer to what is labeled "friend" by the game now, and level 3 being true, honest, deep emotional attachment, almost being completely open with them, so say a best friend, or a spouse you truly love.
So, in concluision, if it is implemented, it should be part of a wider-sweep of things, to increase general relationship realism, and not a "lol gay dwarves are gay" gimmick. I am for this, but not as a "Toss gay dwarves in there for teh lulz,"
Does this mean adventurers will get hit on by gay peasants now?
Because the idea of adventurers being hit on in general is cool.
I have to agree I really want this. Badass adventurer comes to town bearing a few scars, big muscles, and the head of a dragon he just killed?