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