The issue for a lot of people is approval when Halsin is accepted(+1) or rejected(-1) and Shadowheart/Halsin dialog during drow intimacy scene, no matter if Halsin romance was rejected or accepted:
Shadowheart: You know, I had a dream just like this once.
Halsin: A pleasant one, I hope.
Shadowheart: You were in it, so it was certainly... lively.
WTF? It seams like this part of dialog is constructed for open relationship, which has sense when Tav initiate it. However, It is completely out of character in monogamous Shadowheart romance.
Deep thoughts:
Poly/mono relationship acceptance for Shadowheart should be based on her personal quest progress. Polygamy/open relationship doesn't fit Selune Shadowheart romance progression at all. Selune Shadowheart is all about getting away from Shar/groto teaching and if romanced building her own family with PC. While Dark Justiciar is more about having fun since Shar forbids love anyway.

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