Being jealous of an ex-boyfriend or girlfriend is like being left with some kind of scar. It is almost like you have been in a fight and are just recovering from some bruising, only it's worse. I don't believe that most people want to be jealous - they would just rather move on from the broken relationship with their ex and get on with living, but they can't. In short, their emotions are out of their control and as hard as they try to put things behind them it is just not possible. Old memories come up and hit them in the face and send electric convulsions through their soul every time they hear or see their ex with someone else.