Inconsistent writing be damned (I still think Selune Shadowheart should be very upset if you want to open up the relationship with Halsin, the drows, or Mizora, based on how she's written otherwise), this interaction needs to be removed entirely. If you decline Halsin, I never want to hear from him again in a sexual way toward me or my romance companion, but instead of that not happening, it happens in such a toxic way that it would lead to divorce in real life.
Agreed. But I don't think they'll remove that interaction. Because either we like or not, SH is poly (well, not poly but is attracted to Halsin). She and Astarion are Halsin's potential poly partners, and I don't think they'll change that. I think those interactions should be there for people that want them, but there should be a way to avoid them for the rest of us that don't.
That's why I was trying to 'make sense/giving a backstory' to those scenarios with SH.
What I think is a MUST is them checking out the banter/flirting dialogues between companions. In my humble opinion, after you unlocked the 2nd romance scene they should completely stop. And of course, if you decline Halsin, he MUST stop right there and then.
I think they adding poly was a mistake, but that's just my opinion.
Edit: I'm not in favor of the twins scene. I think it should be there, but the whole scene should be tweaked in a way that doesn't portray SH being more attracted to Halsin than Tav.