When I say "thinking about what went wrong," I don't mean sitting on your couch with a gallon of Ben & Jerry's Vientre Plano De La Noche a La Mañana sobbing about how much of a screwup you are for letting your ex slip away. It's overdramatic, and doesn't solve anything. What you need to do is figure out what actually caused the breakup. Two of the most common culprits is when you weren't meeting your ex's relationship needs or if you had some particular behavior that was driving your ex away.
Both of these can be lethal to even a very close relationship, but sadly they do happen, and it makes sense that they can be showstoppers. I mean, who would stay with a person who was actively driving him or her away? Who would let themselves be stuck in a relationship that just wasn't fulfilling their needs? It's harsh, but true.At this point, you have to look over your relationship and see what you were doing wrong. Really analyze yourself and your behavior, and find the problem. Once you've figured out what you were doing to make your ex want to leave, you can get to work fixing it.