I've read a few fan fics that have made me cry, but the first one that came to mind is:
Love Always Remains by harry4lif
I'm not normally a crier, and this got me, so I think it might be what you're looking for.
Probably on Permanant Hiatus
Banner links to my new story Pictures in the Life of a Werewolf! Feel free to read and review!
Banner by the Amazing Nadia/majestic_ginnyAuthor