Confusing Thoughts

I am 27 now and for the past 4 years, I have been having on and off thoughts about a certain guy from high school. I never had a crush on him but he was my date for homecoming senior year. A year after homecoming he asked me to be his girlfriend in a text message but wanted to text and call each other rather than go on dates. I thought that was a weird idea and didn't like him that way so I simply told him that I only liked him as a friend. He then said "You didn't think I was serious did you?" I replied that I did. He then said he thought I had a crush on him based on the way I asked him to homecoming and asked me to be his girlfriend to see how I would react. This was really the last time I talked to him and it was 9 years ago. Yet I still have reoccurring thoughts about him and have never been able to figure out why. I don't think I have a crush on him because I don't feel happy when I have the thoughts , they drive me crazy and I just want them to stop. I have also noticed that I usually only have them in the Fall, probably because that's when homecoming was. The thoughts seem to take over my life and I have a hard time focusing on anything else. It's so annoying and I just want to move on with my life. Any insight on this would be appreciated.