For example, if a character is straight, and your character is of the same gender, should they acknowledge the fact that they are straight even though every such character can still ultimately be romanced? Or should there be characters that are unbending in their sexual orientation, as many are in the real world? I think the latter makes much more sense, but would require substantial changes to romance in the gameplay (e.g. this character will never be attracted to you, this character is more easily attracted to you than others).
I personally like the current romance system, where straight, gay, bisexual, race, doesn't make a difference. You can explore that as your character wants without being limited in any way. And it just doesn't makes sense to me to keep romance options unlimited while claiming characters have preconceived sexual orientations. That is, it seems arrogant to be able to "flip" any and every character because our character is just so great.
This is where playersexuality as a concept comes in - generally speaking, you aren't 'flipping' people; in individual plays, the world is reconfigured so that, by coincidence, what you want is available, this is the essence of what playersexuality in NPCs is. This means that if you pursue an NPC that is male and has established female partnerships in their backstory, and are generally straight-coded (again, I don't like that that's a thing, at all, but it is, nevertheless, in public media... changing this has to be done by gradual steps, if you want it to stick), with a female character, then in this game, they
are heterosexual, and always have been. If, in a different game, you pursue the same character with a male, then they
are bisexual to some extent,
and always were. (Variations and individual elements of personal backstory non-withstanding of course)
As Soul-scar says here - the sudden forced nature of how it's handled in BG3 right now is the main sticking point, and if feels inorganic and forced in most cases. Having more casual character building that can allow the leanings and preferences of the characters to feel more organic and better blended with what we see of their character elsewise would be a good thing... especially if their open sexuality runs at odds with what we already know and have seen - some way to smooth that into something that feels like a natural part of the character would help here.
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For the relationship aside,
I've only ever been bisexual - I know what it's like to be attracted to or not attracted to individual people, but I've never known what it's like to be turned on or off by a particular sex or gender wholesale, so I cannot comment on that... what I can assert is that a relationship is a complicated interwoven thing where all the aspects of it (including the sexual aspect if there is one) influence the other aspects of it, so, for me at least, there is an intrinsic and utterly unavoidable, undeniable difference in having a relationship with a male, as there is in having a relationship with another female, as again there is in living as I do currently in a poly relationship. One is not better than another - they're just different, with different dynamics, and treating them as having the same dynamics would be recipe for conflict and tension.
I don't think it's fair that most modern societies place different expectations on males and females and their expected preferences and signalling - I recall teenage years where it was just generally 'expected' that females were going to be okay and comfortable with fooling around, teasing and kissing other girls, in a sense of 'fun and party' kind of way... even if they were known to be heterosexual, they were often just expected to be cool with that. The same wasn't so for males... and it sucked for those that weren't comfortable with such things.
Because some people just aren't, and that's okay... it's a normal and healthy difference, in fact. If, in a story-telling world space, you make a world where everyone is unilaterally okay with the concept of sexual intimacy with anyone else completely regardless of race or sex, then you have not added anything to the world - what you have done is removed something. You have deprived your world of on element of personal characterisation because you've made everyone the same, and as much as it would be *easier* in real life if everyone was comfortably bisexual... it wouldn't be a *good* thing in my mind, because people should be allowed to be different and to like different things, and those differences are things we should celebrate, not erase.