I feel like shadowheart leaving your group by the end of act2 if you forget or don't bring her to the nightsong is a little sudden and weird. There is no warning that this will happen nor do you even get a chance to talk yourself out of it, like for example laezel. And if nightsong survives the encounter with thorm then she could potentially go to your camp then there is nothing stopping her from recognising shadowheart considering she knows her past, you could even reuse the exact same dialogue(the part with nightsong mentioning her past)

This is even more jarring if you play a 4man custom tav coop, then you might aswell just kill her on the beach because she'll leave either way.

Was this intended? Locking companions like this