it's annoying that people think the OP is a tramp just because she left her ex for another guy. people change. people grow up. people meet other people. maybe she found someone she had a better connection with. there's no sense in staying with someone just for the sake of staying with them; if you suspect you'll be happier with someone else, go for it. don't cheat on your SO, but also don't cheat yourself.
have any of you thought that maybe it's neither of their faults? sometimes relationships just don't work. and just because she left him for someone else does NOT mean she cheated on him. she could have just fallen in love with someone else. things happen and she probably feels bad enough about it. what is it any of your businesses about it? i'm sure all of you have done things in your life that you feel bad about and things that may have hurt someone else. nobody's perfect.