Ok so Ik this is a thing ab a relationship but idk where else to ask this.

So there is this boy who I did like but I don’t anymore, or at least I don’t think I do. So I don’t think ab him actively like a crush nor do I think of him like that. But when ever I actually see him in person I get all flustered and I kinda lose my shit. He also has a girlfriend, which Ik is fucked up. I have no idea what to do or even know what these is taht I’m feeling but if anyone can please help me it would be GREATLY appreciated.