One problem with the movie (spoilers)
I thought the movie was very well written and played, it's fun to watch and made me laugh on more than several occasions. I loved the direction and think that the cast is great too.
So in general, I really enjoyed it.
BUT there's one thing I DO have as a remark - 500 days is a short amount of time for all of these things happening.
It's not even two years for the relationship to begin, to end, for her to get married somewhere in between and for him to get over it.
Seems unbelievable for him to heal such a heartbreak in less than a few months...