I keep hearing wildly inconsistent reports about how Gale, Astarion and Lae'zel behave at the party, and I wonder if it's not so much bugged as that the dialogue there is really confusing. Gale sounds like he's coming on to you even when you're actually in his friendzone. When you pick somebody, everyone else acts disappointed even if they would've turned you down. Astarion used to be all sorts of weird (apparently this was indeed a bug and has been fixed in the last patch).
Shadowheart is the only companion who hasn't left at least one of my PCs completely confused - she's consistently disinterested, as am I in her, so we match! Yay!