But Andrea is neither unlikable in a way that's fun, nor has the opportunity to change and become a person who's happier in and of herself, and that just makes the whole experience frustrating.

What is even the point of a book like that?

[edit] I am familiar with narratives where the point is that the awful or unhappy or self-sabotaging protagonist doesn't change; I tend to find them depressing, especially if they're near-misses on personal growth, but I understand their existence. This doesn't sound like that kind of book, so what even happened?