What is a movie that can relate to this?

is there a movie that is based on a relationship where a girl treats a guy right, and she loves him with all her heart and cares so much about her but than later on the guy leaves her for another girl and he forgets abut her and all the wonderful things they did together, and the girl feels upset and depressed because she loved him so much and he left her and she can't get over him for ages and one day she finds a guy that treats her right that she deserves and her ex comes back coz he realizes that the one that ever loved him was the one he let go and what he did to that girl how he left her the same happens to him and he soon knows what is like when someone you love leaves you for someone else, but the guy was too late to take that girl he let go back, is there a movie like that?