A lot of attraction is physical so when someone looks hotter than the hells and you find out they do things you agree with? What's not to like. Though I will admit both Wyll and Astarion being at medium approval and wanting to bang was a bit off putting. Lazeal was dead so I can't comment on what she would have done. I defiantly made moves on Shadowheart and Gale but Gale I feel like was the only one where it made sense (even though he comes off as a massive fuck boi). Shadowheart should be a lot less eager. I can see her spending time with you in a romantic way but hopping into bed? that not so much.
Shadowheart doesn't hop into bed. She invites you to a night of chatting + some wine drinking. You can kiss her at the end, but the day after she says tells you to forget about it.
