Why would this guy vanish after getting close to me ?

This story happenned a few months ago, before the quarantaine. I saw again a guy I had known 4 years before, when we were still students. Back then, even though we came from very different backgrounds, we immediatly clicked and there was attraction between us. He was interest I think, but he never said it (but he’d walk me home almost every evening, things like that). But he was often clumsy with me (meaning a bit provocative, making hurtful jokes and not picking up on it when I’d ask him to stop).He hot and cold…and he was in a relationship that he was not so excited about anymore (he only told me after a few weeks of flirting with me). But nothing concrete ever happened between us, we never confessed our mutual interest to each other. I was inexperienced, I didn’t know how to reciprocate, and he never said, “I like you.” His attitude and volatility was making me unsure and insecure.

I moved out of town after a few months and he didn’t really try to stay in touch with me (just once or twice, but things were odd and he was still kind of passive agressive, I felt like he didn’t really care). He vanished, and we didn’t talk for years. I had never forgotten about him.

When we saw each other again months ago, both being single, we got along again, we’d tank for hours about everything, and we were both more adult and stable. He kissed me one night and then we started going on dated. I must admit I was excited about it.

We discussed what had happened years ago, he said he was interested but didn’t see reciprocity. He asked if I felt able to be comfortable with him today. And honestly I didn’t know… I think I needed time : he had hurt me in the past by disappearing, and we hadn’t seen each other for nearly five years. I was scared I was not his type of girl and vice versa. He seemed annoyed and said types didn’t mean anything and it was too early to think of our compatibility and I should trust my instinct. I sort of went with it, I wanted to try !

I still found him a bit cold, sarcastic, critical… I didn’t feel at trust with him. I know how a man can be when he likes you (kind, constant, upfront… ) and he was not really like that (he also hadn’t been in the past, often changing and defensive) but I was extremly troubled, interested and attracted. My past feelings were not gone.

He was not very warm and not very talkative between dated. But we were still really getting along, we only went on five dates, but we’d talk a lot and walk for hours each time.The physical chemistry was great (for me, at least). We’d kiss for 20 minutes straight, cuddle… He had to leave for a month long trip… a week before he left, we had heavy petting one evening, for 2 or 3 hours. He left at 3 or 4 am, he looked strange, a bit awkward and cold. He didn’t write to me the day after. It confused me. I knew he had to work so I sent him a text saying I hoped he wasn’t too exhausted. He said he was far from regretting what had happened.

Then, a week later, we went out again and had sex at the end, I slept at his place. And then he left for his trip and seemed to pull away…writing less, not asking how I was or returning my questions… so I stopped initiating contact now, and he hasn’t tried to contact me or to remain friends with me, he claimed to find me special and interesting.
It hurt me, and I was confused. I find it douchy. Why would he come back after years to disappear again like that? How would you react ?

Any opinion would be welcome