I don't agree with that. In the Selune ending at least whether you save her parents or not she makes it clear she wants to continue the relationship and she'll even stay with you if you become a mind flayer. I do think it's weird that she says "seek me out when you have time" if she saves her parents but if she lets her parents go you will continue traveling together immediately after the events of the game. The discrepancy between saving and letting the parents ending go makes no sense to me but there's no lack of commitment as your character will go to her after some undetermined amount of time.
It's the third time throughout the playthrough that you have to confirm it to her. First time I'll give a pass because it's just after the Nightsong stuff so she's emotional. Second time however is basically a marriage proposal a long rest after the beach scene. Yet she's still doubtful and needs confirmation again at the end of the game. And yeah, the parents ending is weird in that regard. Even the parents are completely cool with you. I did like that touch (need to talk to the dad before long resting after saving em). But then it's ruined in the ending again.
