I have seen so many posts on fb or even here where people ask how to make their ex jealous, or how to take revenge on their ex bf/gf. This happens in real life too (at least around me). in my opinion, they still have feeling for their ex or else they won't be wasting their time trying to get their ex's attention. I told this to some of them but they are in denial. I think they are ashamed to admit that they can't forget their ex.