I don't think many people get the exact romance they want from any story they read/play/watch, but because you empathize with the characters in the story, you're taken along with them during the narrative. When someone says "love leads to sex but sex doesn't equal love" I find it a bit of a non sequitur, we're being told a story with casual sex in it, you only seem to be taking issue with it because we've all been conditioned to expect 'romance' be a part of the game and you're afraid the casual sex is what Larian considers a romance plot-line. I think it is what it seems to be, casual intimacy that may lead to further intimacy between the characters.
We have companions who are happy to have sex with you, and we have companions who aren't, in fact, their interactions during the celebration scene seem to be Larian telling us how each character treats intimacy on these levels.
The above also seems to be in argument for the removal of the depiction of sex from the game, I'll never be in favor of censoring something because if offends someone. But I understand where it comes from. I like comics, for a while they were all-ages fare, but as the stories became more mature and adult oriented, the absence of sex became a hang-up, the comics trying to tell adult stories didn't feel complete without it, comics in other countries which never truly pigeonholed their comics by age bracket are good examples of the diversity of story that could be told in this medium. The inverse is also true, I'm a fan of comics, so I am also well aware of what happens when sex becomes a gratuitous add-on, with little function beyond titillation. That line is something people argue over but I don't think we as fans of RPGs should be trying to tell creators to check themselves like this.
In summary, 90s comics suck...that's what we're talking about right?