Very interesting to read what makes you want to reread a book over and over again.

I feel the same way about Harry Potter, there are very few books I actuallyread ever again after finishing once, but I can always go back to these.
And I actually read Hunger Games a few times and even liked that the ending wasn't all to happy, even though I still had my issues with it. (Spoiler Alert: I just didn't ship Katniss with Peta at all.)
Since my bookshelf is full of happy endings, some earned some came out of nowhere, I enjoyed this deviation from the norm.