I also made an account today just to post about this (but at the time didn’t see this thread).

I wanted to:

1) chime in here to say that I am also extremely disappointed in the current ending and have little interest in finishing the game now, for all the reasons highlighted by previous posts and

2) I feel like (while the character certainly deserves the Definitive Edition revamped quest treatment) even something as simple as some player dialogue (so no voice acting required) could provide a quick improvement,
during the romance “go to hell together ending” stating that they’re just either A) going back to Avernus until they can fix/replace her engine (ie. It’s just the start of another quest and not eternal damnation) or B) going to do some sort of a Persephone arrangement, where she has to stay in hell until her engine stabilizes and then she gets to go surface side again for some period of time.