The SH we get in act 1 and most of act 2 is kind of in-between Shar/selune I think. What I mean by Shar SH is her full embrace of Shar and her teachings in act 3. Have you seen the sex scene for evil SH? It's very aggressive lol
Though I believe that scene happens after evil SH kills her parents? So that means she goes even longer without having sex with Tav. And at that point she sees you as casual too anyway.
If she sees you and Halsin as both casual then I don't see why she wouldn't share, even if she hasn't slept with you yet.
