How to tell if a guy is trying to make you jealous?

I was walking with some guy friends to class and I know this guy who always looks at me saw us walking together. I could see him from the side of my eye looking at me and my friends, but I didn't look directly at him. Later in the hall when I was alone we passed each other. I tried to make eye contact, but he walked pass and seemed to have avoided me. Then while in class he started talking to this girl who I know has a bf, but he was asking her to go for a walk outside with him and he was talking so loud. Of course she refused and he left the class, but anyway, I had a feeling that he liked me at one time not too long ago, but now he is flirting with this other girl who has a bf. So why is he trying to make me so jealous? What do guys expect to get out of this sort of behavior?How to tell if a guy is trying to make you jealous?
he wants u to want him just play hard to get but dont get all seriouse i mean REMEMBER play- as in its a gameHow to tell if a guy is trying to make you jealous?
Well ima a guy so yeah hes trying to make you jealous and wants you to like him back. By the way he still likes you.