Why after 2 years I am unblocked?

A guy I was talking to blocked me on snapchat about 2 years ago when we were in school together (we were both 17 at the time I was blocked) and I have known him for over 10 years and we have a long history together. I stopped the talking because I knew he talked to other girls but I found out he actually liked me. I did make him jealous on snapchat by posting pictures with guys which I think caused him to block me. We also went to school together and we graduated last year. I recently saw him 2 weeks ago at a festival while I was visiting home as I am away for college. I noticed when I saw him he was staring at me a lot. The last time I saw him was at our school graduation. Today I just found out he has unblocked me as occasionally I type his username in snapchat to check if he has unblocked because I still like him. I am unsure if he unblocked because I saw him recently as when I saw him everyday at school I was still blocked and have been for 2 years until today. He does have a girlfriend but should I add him back or is it weird? Even just to be friends cause we were friends for so long?
Why after 2 years I am unblocked?
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