What movie is this one that i am looking for? romantic one?

i watched this movie the other day it was about a girl that her fiancee dies and she meets this other guy randomly and he kind of looks like him. so she decides to meet him again... after they fall in love but she s not sure what she wants she tells him to write a letter about how he feels about her and she ll do the same and they ll put it under a tree in central park and they ll meet again in a year to open and read it