It's definitely Deep Love, Again. If you still like Deep Love you'll probably like it. I feel like releasing a continuation over 10 years later was silly when most people that liked Deep Love back then probably aged out of it, but I got into it late, anyways.
The ending was also really hard to accept. Initially I felt it invalidated the entire series, but after some reflection, I think it brings the story full-circle and provides closure in a way Reina's Fate didn't.
I read it through MTL, but if a dedicated translator is interested in helping, I'd like to scanlate this. Just message me or respond to this post.