JFC, no-one is dragging Astarion to the brothel against his will. Depending on what stage his personal quest and romance is at, he'll decline sex. You don't even have the option to persuade him into it like you do with Gale. If he does accept, then he consents to a scene that he wasn't ready for, and the only issue that I have with the whole situation, is that your character should have had the option of stopping the scene when they noticed he wasn't okay, but you don't. This whole game is actually awful about aftercare, but that's a personal peeve of mine that not everyone shares.
At no point while i was romancing either Lae'zel or Wyll did I ever feel like the game was punishing me for not being poly. Realising i had locked myself out of seeing certain options if i wanted to keep romancing one person was mildly disappointing, at worst. As I've already said, Halsin is easy to shut down, tell him no one time and it never comes up again, hardly meddling. The game gave me plenty of options and warnings about their preferences (based on the dialogue that occurs if they are in your party), and how they would likely react to infidelity. Amazingly, i did not cheat on them, and wasn't at any point forced into doing so, nor made to feel bad about not doing so. The run where I romanced Lae'zel was also a Durge run where i raided the grove, killed everyone at the last light inn, and dominated the brain in the name of Bhaal, so quite evil.
The only time i ever found myself in a sudden and unexpected love triangle, was when i changed my mind about who i was trying to romance during a run. I flirted with Gale in the early game and tripped his initial romance flag, but then locked in a relationship with another character, which prompted a conversation with Gale. It was a sad conversation but surprisingly reasonable about wanting different things.
