the guy i lost my virginity to is acting weird?

[Dez]

So i had a fling with a boy from freshman year until the summer going into junior year. i really really liked him but our timing was always off so we never officially dated. well this summer we liked each other and one thing led to another and we had sex...3 times. we were each others first.

but of course, he wasnt ready for a relationship because it was summer and he just wanted to keep partying (hes really popular :/) and i got so mad so i told him we are done.
i started seeing other guys and going on dates etc. and he knew this because i told him.

well then things got weird, he wouldnt say hi to me at parties, he unfollowed me on twitter, told me mean things like "i'd never date you ever." and it really hurt my feelings.
we haven't talked in about 5 months now, however i saw him at a party like 2 weeks ago and when he saw me he ran the other direction
but once i left the party he called me two times but i missed the calls and when i txted him back saying "what do u want" he never replied....
and now he keeps liking my pictures that are old! so hes obviously creeping.

but idk what this means? is he just messing with me? please give me advice on what you think hes doing.
and i know for a fact he honestly liked me when we had sex, he'd always tweet about me and his friends told me he'd talk about me a lot. so i know it wasn't completely using me, he did have some feelings

[Dragos]

Sounds like he still has feelings, however he seems to be stuck between finding himself and partying

[Finwie]

He likes you or feel some kind of connection with you since you were his first. But now he's acting out on you because he didn't manage to keep you. Maybe he's jealous, even.

[becca]

He is probably jealous but doesn't want to apologize for his his behavior. He wants you to take the blame for things going sour. He sounds kind of immature! But he obviously really likes you...