Moving on..

I fell really hard for this guy over the summer and I thought things were going well until he ghosted me out of nowhere. I would be over him by now but I have to see and work with him everyday all day (he’s a manager at my job). It just makes me sad, the way things went and now we’re getting back to normal, as if things between us never happened, but it makes me miss him... I just need advice on how to move on from someone you could’ve seen yourself with in the long run?