I mean romance is fundamentally not a logical thing. People are weird and inconsistent and do things for reasons that sometimes only make sense to themselves individually, or stop making sense the moment they put it into words. Add to that high-stakes, high-pressure situations and people only get weirder. There's also the issue that sometimes the companion doesn't really know if they want to sleep with our character or not. RPG companions are usually mired in trauma and issues of one sort or another that they need to work through and figure out. Or they just haven't figured out how they feel about us yet. Here's an example. When my grandmother was stressed, she would often not want to eat. She'd just skip meals. When I'm stressed, I immediately start looking for something to eat. People react to stressful times differently. A high-stress time could just ruin the mood because they have too much on their mind. Plus there's also the narrative aspect of it. It does make sense that from a narrative standpoint, getting together with your love interest serves as part of the big climax of a story.
Ultimately though, I agree there should be more variety. I like that in the dragon age games, most of your romantic relationships pretty much lock in by the middle of the game, give or take.
