The other crappy thing that was discussed on the forums about this exchange and actually the whole path is that as soon as Astarion ascends you cannot even tell him you love him. You can only ask him for a bite and sex or create conflict. The game assumes you're a selfish asshole who pursues him for their own goals or is terrified of him and has buyer's regret. It doesn't allow you to roleplay otherwise. The only semi-romantic option is telling him you hoped he'd learned to love you, but it still doesn't specify that you do. You can only lecture him about how you loved him before ascension.
I think it's because writer wants to show that vampire emotions are changing and now feelings are expressed in lust (just a guess). But, as I said, it can be shown through Astarion. Use our characters for this... sloppy.
