This is a D&D game, and Larian are our dungeon master. I'd rather have one that's open to player requests about relationships, than one who shuts me down at every corner because they think halfings involved in romance is gross (looking at you, Kingmaker).
I think it makes sense that certain characters only allow certain characters to romance them.
Reality is racist - will always be and that is just the highest truth. Doesn't bother me.
Racism is not racehate.
It ultimately only borders on personal preferences which is a core expression of free will.
Minthara is a Drow for example. Everybody knows by now who the Drow are.
It would not make sense in my opinion if they truly find some Races attractive in itself - if not for the purpose of using them in a scheme and manipulate them with their Darkelvish booty.

But otherwise they are probably narcistic as they come.
The futher a Race deviates from the likeness to their own Race, the less they would see them as "worthy sextoys".
And the more it would become disgusting to them.
A few very excentric fetishist groups and/or individuals are the exception of course, just like in our real world.
But ultimately - fleshy beings are visual in their attraction.
Drow society will not find Gnomes, Halflings, Dwarfs, Kobolds & Goblins as sexually interesting as even Surface-Elves or Humans most probably.
It would feel very immersion breaking otherwise.
Faerun is based probably. Especially since there are no big-tech massmedia brainwashing people with "race-less" Agendas etc.
And the Drow especially have an innate history & nature influenced "by a deity" to be lured to racism and rank-like thinking.
I really hope Larian will not forget or ignore that.
Immersion is everything after all.