I just feel like there is some upsetting bait and switch going on with Astarion’s character. The early acts give you the strong impression that he has a domination kink, which I frankly thought was cool to see represented in a video game romance. The problem is, if you don’t ascend Astarion he becomes completely fluffy and sweet with no indication he ever had a kinky bone in his body; which is also inconsistent, in its own way. Now, though, if you do choose ascension the relationship just feels non consensual now. Which again, is not what they tease before that point.
I have always felt like you’re making a devil’s bargain when you kneel. In exchange for freedom you choose a life of sin, luxury, decadence and pleasure. You can’t leave, and you’re not an equal partner, but that’s a price you can pay.
As far as Astarion. Even Ascended, it felt like he needed Tav. Except that’s weakness. So he exerts control in order to maintain his self image and prove that he has power even over his own emotions. The only way for him to feel safe in a relationship on this path is to dominate it.