Originally Posted by Filia
Is this something that got changed? I remember when watching the YouTube videos on release (I didn't play all the romances myself) SH and Astarion were pretty fine with it, same for Halsin.
SH: "I'm not jealous, you know. If I wanted to bed something loyal and pure, I'd find a swan." and she goes on that you shouldn't forget her needs and that's about it. Doesn't sound like she is totally against that, she just wants to know it in advance.

Tav to Astarion: "Like you wouldn't have jumped at the chance!"
Astarion: ""Well of course I would have [...] So what was is like? Tell me everything."

Halsin talks about how our hearts are free to roam and we don't need jealousy (but on another line he is like "hopefully I'm not boring now". If he doesn't care, why does he compare himself to her?)

Either way: Cheating is one of the worst things to do and you are in relationship with every companion, so they should break up with you. Larian could've made a statement on how hurtful cheating is and how important communication is, but it's not the first thing they sacrificed for adding the forbidden fruits without any regrets.

EDIT: Just saw the new post about that is hasn't been updated. Not sure if we just have a different understanding, but to me it feels like SH is pretty fine with it and not just ok.

Also she insults Mizora(why?), calls her "inferior goods". Asks to not forget about her and that she needs your attention too(why?), asks to ask next time beforehand(why?).
Regarding swan line, it's more like she tries to insult you, because you can use "swan" line in act 2 if you ask SH to do poly with Karlach(obviously she refuses) "I am not a swan to mate for life, I want to be with both of you" is the quote and she goes "nope". Also she falls into Sharran condition(thats why I believe it fits Shar path more) and brags about Sharran time. All in all her reaction is "fine", I don't see her breaking up over this with how she is portrayed overall, but she is not fine with it.

If you ask your partner before you do the deed(thats what SH asks you) - cheat becomes not a cheat at all.