So I've done a few playthroughs and my go-to love interest is Shadowheart. I romance her and even Withers acknowledges the relationship. However, the other companions seem completely oblivious to the romance and keep on offering themselves as an LI as if they've never seen us kissing or sneaking off. I mean, it would be fair enough if they'd say something like "I know you have a relationship with Shadowheart, but I can't help but feel strongly about you as well" or something to that effect. But whenever they start their romantic sequence towards you, it's as if the relationship I'm already in has gone completely unnoticed by them even though they were only meters away from when I kiss her, for example. So that kinda breaks immersion for me because it feels like a start of a sequence that comes out of nowhere that was just shoehorned in there. I guess that it's because all companions have a starting point of their romance sequence but I can't help but feel that they shouldn't have been done completely parallel from each other.
For example, Halsin, because I remember him being devastated when I turned him down as if it was something he didn't expect. I didn't even have the option to say I was already in a relationship. And I'm used to games where you have to initiate romance and there being logical limitations, so companions could end up saying no, which is very normal in life. On the one hand I get that Larian wanted to do something completely different and reversed the process, but on the other hand I can't help but feel that they took it a bit too far with how "thirsty" companions are for your character and then being oblivious to other romances. You'd think they'd be fighting over you, but no, when you're in a relationship nobody is aware of that the moment their romance sequence starts.
Anyways, just some of my thoughts that I wanted to throw out there.