Sorry for the double post, but something interesting just occurred to me. I was reading another thread where someone, speaking of the Emperor, said he's basically just a reflection of the player's opinion of him. If you think he's trustworthy, then he is. If you think he isn't, then he's not. Which is obviously not how it would work in real life; if he were truly trustworthy, he would be that way whether you trusted him or not.
I feel like the AA romance is very similar. Like I've mentioned before, the clips of AA I came across on social media (less so now that you lovely people have directed me to some great channels) show the worst options for dialog, and Astarion reacts accordingly. If you tell him after the ritual that you hope he learned something, he gets hostile. If you try to break up with him, he gets hostile. Basically, if you treat him like you assume he'll be abusive, he'll be abusive. But if you lean into the dark romance aspect, he'll lean into it too, showering you with affection and praise. Just look at the difference between the two ways he tells you to go mingle in the epilogue party, depending on if you tell him you still want your freedom, or if you, well, say pretty much anything else. In the first instance, he gets super nasty, calling everyone else your "so-called friends" (pretty common abuser tactic, to try to isolate you from your friends by insulting them). In the second, he encourages you to mingle quite happily, even implying he's happy if you tell him you think the others are doing well (in his own, cheeky Astarion way). Am I saying the way he speaks to Tav during the more hostile interactions would be okay from a real life partner? No. But also, a real life abuser is going to abuse their partner regardless of how nice they are to them. It might put off the abuse for a bit, but there's only so much walking on eggshells you can do. There's nothing in the text to suggest that a Tav who goes along with AA's scheming, whether sincerely or for self-preservation (and the game makes no distinction; there's no deception checks or anything when you agree with him) will eventually see their luck run out. To my mind, he seems genuinely sincere when he does things like thanks Tav for trusting him, tells him he's blessed to share his life with her.
Again, I'm not saying this is desirable for a real-life romance. It's a dark romance fantasies, but dark romances can get, well, dark, and this one does even if you agree with him (just in a different way than you get when you don't agree with him).
I almost wonder if the discrepancy can be explained by the writers focusing not on making Astarion outright abusive (patch 6 kisses aside), but on the desire to truly let the player roleplay the relationship the way they want, not just in their dialog options, but in Astarion's personality. If they want to roleplay as a regretful Tav who no longer trusts the man they fell in love with, Astarion will become an evil, possessive Dracula type. If they want to roleplay that they think his wickedness is great, actually, he basically becomes Lestat (from the second book onward) with more Machiavellian ambitions.