It really feels like the author picked and chose the most important things to resolve given the situation. And I think they did a really good job of it truthfully. I understand why people are upset at the idea of resolving things in a conversation, but if there were ever a series where that was possible, it would be this one. The act of unveiling the disgusting parts one was hiding has been put forward as the way to move on and accept them, and that this is a proper path to healing. I think that's exactly what we see. And with that what needed most to be resolved is resolved, and that's absolutely an acceptable place to end a story: to not tie everything up in a neat bow, but to have a very clear focus on a part of the character's lives that the story is about, and resolve it when that conflict is resolved. Like in Niji's case, they haven't made up or figured out how they're going to move forward, but it was that conversation where they put forward what was inside that created a path toward some resolution, and that act itself, not the resolution, is what's being celebrated.
I can't imagine how it must be to know you'll never be able to tell the ending to a story that you had envisioned, and to have to write something else instead, to just do what you can. It's never a satisfying ending, because the story isn't done. But in this case, I think it's quite close. One more chapter of pacing to let things settle and develop at the end and it would have honestly been great. But I'm glad we got this story, and I'm glad we go the resolution we got.