I (20F) unexpectedly saw the guy (20M) I quietly loved for 5 years and froze. How do I move on from this?

I know this isn’t technically a relationship, but this has been affecting me so deeply that I wasn’t sure where else to ask.

I (20F) had a crush on a guy (20M) in high school that eventually became much deeper than a typical crush. We were classmates, friends in the same group, but nothing ever happened. He never knew how I felt. Over the years I genuinely thought I’d moved on.

A few days ago I unexpectedly saw him during my internship. He didn’t see me. Today, on my last day, I unexpectedly crossed paths with him again. This time I was only a few meters away. I kept waiting for him to notice me so I could naturally say hi, but he never turned around. Instead of walking up and introducing myself, I froze. Then other people came over to talk to him, and the moment passed.

What shocked me the most is that I genuinely thought I’d moved on after four years of not seeing him. I had reached a point where I rarely thought about him anymore. But seeing him twice in one week brought everything back so intensely that it feels like I never moved on at all.

Has anyone else experienced this? How can someone you haven’t seen in years suddenly affect you this much? Does this mean I never actually moved on and just buried my feelings, and if so, how do I finally move on for good?