Struggling to get over someone (m24) I (21f)never dated, feel incredibly sad and pathetic?

I had a short fling with a man over a year ago. He wasn't my first so it wasn't that kind of attachment. He ended things because he was graduating college at the time. Just I have never stopped thinking about him, I don't know why. I've dated other guys since him and stuff so I've tried letting go. It's just all I think about sometimes is him. I never had this kinda thing with any of my partners before him, even the ones I was actually dating. I just don't know what to do to get him out my mind, I slept with someone else and met new people. I did the basic things people suggest to get over someone. I slept with someone else. After I just felt awful like I cheated on him. I mean I have distant contact with him, but not really we have some friends in common but that is all. So, I don't ever really see him either. I feel like I'm losing my mind. I don't know what was so special about him, I honestly don't. Sometimes I get a feeling I'll meet up with him again or something. Idk I'm crazy, I mean I'm not stalking him just to let you guys know. I don't know where he even lives or works so yeah no worries there at lease. lol