I don't know astarion enough to say one way or the other. But gale made intentional choices that led to his punishment it wasn't some random act of chance like karlach. She wanted a job and it happened to be with gortash who sold her as a slave to zariel who then experimented on her to create a demon hunter soldier with an infernal engine for a heart. Nothing about her story was jn her control where as gales lust for power led to his current issues. Wyl is similar but his was a lose lose situation. My point being if gales ending is he can't chase after magic that's a proper ending where he can move on and find other ways to live. Karlach literally can't and her only mistake was she happened to end up working for gortash and she was way too trusting.
That's why I was talking about Astarion (and Gale) and not about Karlach. I understand why people would want a happier end for her, she is this faultless cute girl that everyone would agree deserves happiness. Still I'd say that with the current epilogue, a headcanon in which the whole gang is back together again after the next half year has passed, isn't that far fetched. So it's not a perfect end for her and Lae'zel yet but a pretty hopeful one at least.
