Be believable Larian, plot holes for the sake of angst and poignancy with nothing to back them up make zero sense, something that happens a lot in this game towards the end and not just to Astarion.
I agree with nearly everything said by the OP and many of the suggestion they make, and comments from other posters, are things that I believe almost every Astarion fan has either thought or posted about before.
I can't say this is a plot hole. Apparently, this must be an artistic trick in which Astarion deserves redemption by sacrificing the sun for the sake of the people he ruined. Redemption must be bitter. Another thing is that I hate all our actions at the end. We can't run after him. We can't comfort him or anything like this. I also hate how he reacts to our suicide. All final reactions are performed very poorly. Also, do not forget that Astarion is 200 years old, many options for curing vampirism do not work for him. If they add some cure to the game, then his lesson will not be learned.
