How do you make a guy jealous if he already had a girlfriend?

You must have split-up for a good reason. The best thing to do is not even let her know it bothers you. If you see her smile (even if you are upset and heart-broken inside) and start dating again. There is a possibility if she sees you dating other girls she may come back. Don't waste your energy trying to make her jealous. It's simply time to move on and if you are meant to be together you will be. Good luck Marcy You can only make her jealous if she likes you more than the dork. If she is only luke warm towards you and you do something that you think will make her jealous, and she doesn't get jealous, then who's the dork? If she likes you more than she likes the dork, why isn't she going out with you? Obviously you aren't matching up with the dork in her eyes. Forget about making her jealous; jealousy is a juvenile emotion. Cut to the chase and ask her out. Put the ball in her court.