Advice !

So there's this guy that works with me and everytime I see him I feel a rush in my chest. But he always calls me " hey beautiful " or " hey you ". " hey boo" he's so hot but I feel like he flirts with other girls I haven't seen him personally just the way he acts seems like it . So one of my co workers told me that " he has a girlfriend but he may be wrong " but I don't want to seem easy anymore like a flirt too so idk how to show hard to get or make him want me.