100% agree, a lot of decisions made by the writes are mind-boggling. Both romance endings (Astarion ending) are unsatisfying, unexplained, unfinished. Companions relationship that sprout from seemingly nowhere are even more awkward.
Romancing in this game is naught but marketing to attract those interested in internet porn.
It's silly at best.
Serves no purpose.
Either that or we got the "Cyberpunk 2077 treatment". In which we got a half-cooked product, where the 1rst act is nicely polished (to hook you) and then everything starts to lose quality the longer you play. At least it feels that way.
But talking specifically about romance, how can SH (which is arguably the "main character" of the game) can have the possibility of behave so differently that can change the player's perspective of her?, The same can be said of Halsin (for what I've read), he does a 180 in act 3, without any type of foreshadow. I don't know about Astarion but it seems he's badly influenced by "the Halsin effect".
So it's almost clear that they used romance as a marketing campaign more than anything. I played a bit EA (not that much, I like to play finished games) and had forgotten about the game. Then released date was close and suddenly you could find Astarion and Halsin doing the bear scene everywhere on the internet.
And I hope they fix all this (eventually) on the base game, wouldn't want to be surprised with a DE, that solves all of this situations but you have to pay for the game again...