Im loocking for a movie,it's a thriller ,I saw it a long time ago,so I did't remember plot exactly,but I know that is about bookshop owner who fall in love with one girl,and at the end she kill him... and that is all I remember.Can someone help me?

It might be.. Unfaithful

Unfaithful (2002) - IMDb (http://www.imdb.com/title/tt0250797/)