Here is what I want to know. Does the game somehow let you know that the NPC's that can be romanced could go either way? Would my character ever know that without ever having read one single thing about the game.
I haven't played so I don't know but I would think that if it was left either way and that choice did not come up in the game that a straight person, nor a gay person, not a bi or trans person would not think it odd at all that this person was interested in them. They would just think, "he/she goes my way. Woohoo."
I mean, when I met my hubby I didn't ever ask him, "are you straight?" Soooo....it really shouldn't bother us either way when playing the game. It should just feel right during the gameplay for whomever you are.
So does the game let you know, "hey, I'm Preston and I'm Bi."