I'm sure they could've written Shadowheart being able to be convinced into a threesome without her cucking the MC. It's the established relationship trajectory warping in the presence of Halsin which is the main culprit here.
Nicely put. The scene and the banter are not in line with what you would expect from Shadowheart. It contradicts and in all honesty ruins her character. They could've removed the banter and written that scene with her rejecting Halsins proposition. Then leave it up to the player to have a persuasion check to change her mind (although I think a lot of folks wouldn't like that either lol) but they went with her strait up chasing Halsin and ignoring the MC.
A romance path that ends in a partner revealing that they want someone else is not an appealing one.
