I'm not happy with the ending I got either. I'm guessing the game bugged out on me on my Good run, Astarion just runs away and the final credits start. Never had a conversation with him after that. Very sad to say the least, and what happens to him afterwards, what happens to us as a couple??? What am I to think, especially knowing that the night before we've reassured each other to be together and then just ubrupt ending out of nowhere...
But what bothers me more is my Evil playthrough, the ending with him is just awful. If you want to stay with him you'll have to be converted to a spawn, there is no other option to stay in the romance with him at least on my game. No option to persuade him to make you a true vampire or for you to stay "warmblooded" as you are. It's either his way or the highway. What kind of logic is it on my part to submit to slavery after everything he told me about his struggles as a slave, after everything I saw myself throughout his quest line? More so, my char is a one-turn solo boss killer and why would I want to degrade myself to a servitude as a slave. He sees you as a powerful ally, yet only stays in the relationship if you're a spawn.
And if you control the brain you somehow cannot direct the brain to not influence Astarions mind. Not sure why you cannot have the option to rule the brain together?
I don't know, maybe my game is really bugged but all the options suck so far.