Why is he acting this way?

As a teenager I attended martial arts with my brothers and was the only female there. The class was located just a few buildings away from my home. ( My father would often breeze on the porch and watch us practise) There was this hot guy, a year older (second in rank from leadership) on whom I had had a huge crush. I was friendly with everyone except him as he was so serious and distant from the group. After class he would pull my brothers aside and whisper to them to watch over me, protect me from the other guys and take me home safely lol I found this so amusing. (Mind you he hardly spoke to me or even smiled). I heard he once confronted one of the boys I became close with and asked if we were an item... they couldn't stand each other. His cousin came over during a class to confirm whether I liked him or not (something I denied as I was so taken aback and embarrassed to admit at the time... he told me I wasn't being honest and left to whisper something in his ear). He was cool and considerate outside of class settings and I discovered we shared a lot of common interests from our few bump-ins & that he had sad childhood. He often had martial arts movie recordings on his phone that he would bring for me to look at. He was talented and reminded me so much of my father. Our instructor moved away after only months and class was cancelled. My crush lived in another neighbourhood and since then I had only seen him a handful of times. He once suggested to my brother that I join him to catch the bus to school but I didn't know him well enough and thought it would make me look desperate since we weren't even friends to begin with. Many years have passed and to this day whenever he sees me he would barely speak and act distant like he barely knew who I was but would acknowledge all my siblings so warmly including my little sister whom he barely knows and would call her my own name and wave etc. Once he tried to make me jealous with a girl he was dating. What's his deal?
Why is he acting this way?
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