Another option would simply be to have the player chose sexual orientation upon character creation. That way only companions that match would be available for romance, and all dialogue options with un-matched companions would always be seen as friend-only.
I'm certain this would give people the best possible experience, because it would mean other characters could see/sense/whatever (through subtle cues that can't really be integrated in to a game) what kind of people you are and like, and they wouldn't try to hit on you if they knew you're not interested in their sex.
I still preferred Dragon Age: Inquistion, because of how awkward the romances could be, when people (both the main character and their potential love interests) weren't yet quite sure of where they stood in relation to each other. If you didn't, for some reason, cue on that Dorian was gay at least you could test his conviction and fail. I think friendship and just being friends used to be better represented in games.
I get what you mean by 'playersexuality' being the best option. You're options in a game are very limited simply because there is only so much time the writers have to write a romance. Better to have more than one option (or none as gnomes, halflings and dwarves found out in BG2, despite it having some of the best romances otherwise). 'Playersexuality' isn't a problem unless it means that every damn person wants you. If everyone wants you then it puts in to question whether they really want only you to begin with or if they're the kind of people who would want anyone else too under different circumstances. No one's that special, even if you're a damn model or a millionaire, or both, not everyone is going to want you.
If there are limits to wants, then when two people match, it's what special is truly about, quality not quantity.
