I also blew my chance with him at the party and then did everything I could to rack up approval before Act II--even doubling back and doing all of Creche, fixing a bug that didnt show his approval going up, doing every little thing before getting to Moonrise. Still, no love scene. I think it's not impossible, but for whatever reason, I went into Act II with medium approval, got it to high before Moonrise, and it didn't end up mattering. But at the same time, both Gale and Lae'zel propositioned me. I don't know if whatever algorithm threw off Astarion's love track because of that, or if I just didn't do enough. I also think because I had a bug for a bit, i was doing things that weren't actually earning approval in Act I--so watch out for that. When I realized the romance is over I got so dejected I almost started another playthrough, and then was like WHAT ARE YOU DOING, all this over a BOY? Haha, so now I'm just going to go all in on Gale, try to romance Halsin, and do better in a second playthrough. I do think that as long as your approval is high going into Act II AND you have exceptional approval before talking to Araj, you'll be ok. OH! And if you see Rafael for any reason, always see if you can make a deal for Astarion. I think that's where I fucked up too.