This is the truth about why men come back. They come back because they never actually wanted to leave, they just don't know how to talk and deal with issues. As a consequence to their own inability to communicate, they choose what seems (at the time) the easiest option...leave. RUN AWAY! AVOID AVOID AVOID. Ultimately however, issues surface. Then they find themselves alone with their relationship problems...that's when they come crawling back.
A really mature (and unselfish) man is comfortable talking through relationship (and personal) issues. When a man like that breaks up with you, he'll never come back.
My opinion is that you shouldn't let a guy come back. Just accept the break up, and be grateful for the happy times you had together. You only live once, there is no point to stress about something you can't control. And I know it is hard...my boyfriend just broke up with me two days ago (and I just found out that my mom is terribly ill with cancer). So if I can keep a smile on my face and move on, any woman can.
Don't waste your life waiting for someone. You are too good for that.