I was thinking of this earlier and have an example of an unsatisfying ending. I was reading a book that had a very beautiful, tragic wrap up that I was really pleased with. It hurt in the right way. But then, during the last chapter or the epilouge, I can't remember which, the author basically wiped away everything prior that had happened and completely changed the narrative to make a more upbeat, happy ending. I absolutely hated that she did that and still think it was a cowardly out. My sister, who recommended the book, liked the ending so that it was less depressing.