Oh yes, definietly ...
Presuming you have Shadowheart.
She is the only stable in my group and yes, I know, you don't like her. But you can just go to where Gale spawns first and collect him and/or free Lae'zel and then go back to Astarion and kill him in dialogue.
oof, that's a rough choice, recruit SH and be able to kill Ass in dialogue, or not recruit SH but cannot kill Ass. No win situation there ^^
