Speaking of the "mortal ending". That's another reason why all this dialogue is so weak. If you go to the final battle, and ask to make Tav a vampire afterwards, Astarion "approves".
And there's a dialogue here: Player: Actually, no. This isn't what I want. Astarion: This isn't what you want yet. I'm sure you'll come around in your own good time. Astarion: But until the moment's right, we can still be together. We can still taste all the delights of this world. Astarion: We have a beautiful, bloody future to look forward to, my love. I can't be sure what it holds for us, but I know one thing. Astarion: This is going to be fun.
He reacts much more calmly, and most importantly he doesn't break off the relationship. The whole third act is going to take a long time to improve. The romance with Minthara, too, so. With Lord Astarion, details can be added as well. I think after the ritual it's worth adding "conviction" to wait. And if it fails, it will be yes or no. Then it would lead to the already existing "mortal ending" without skipping content.
Also there are no details about it in the epilogue, it's all spawn. But then you should have added that he talked Tav into it in a couple of months. I wonder how they will build an epilogue to this ending. This part will be told by the narrator, or as some dialogue, or Tav will still remain mortal.