why do they cheat?

Why do you break down if everything with your boyfriend is going ok? Sounds to me like you shouldn't have anything to worry about, but hang on there hunn.

Take Care,
Sarah-Joy

she breaks down because she thinks he will cheat on her again and its heartbreaking when you know that you werent the only girl in your guys life. but dont worry you will get over it just dont get too overprotective, ask him if you can go places with him and things and call him regularly.
have a heart to heart and ask him if he has ever cheated/ ever will cheat on you again.