He ignores me but I'm so confused about his behaviour towards me?

We have a friend group of 6. We've been friends for 5 months now and he is technically my first close friend in Uni. To begin with, he is an extreme introvert. Whereas I am an extrovert. In the beginning of our friendship, I shared a lot about my life and he also used to share small things with me. But then one day we got into a fight, well it wasn't a fight, I was upset with him and didn't wanna talk. I was waiting for him to say sorry but he couldn't say sorry and told the other mutual friend how he was in pain because i wasn't talking. And then I realized and talked to him. After this, he talked to me like a baby.
Coming to present time, he ignores me like hell. He replies to my texts late, he consciously avoids sitting beside me in class, he deliberately behaves rude with me, teases me in front of other friends and also while we two are talking, he takes pictures with everyone but not me and he tries to make me jealous by talking to other girls in front of me. He also deliberately doesn't like my posts. On the other hand, he notices many details about me which I myself don't remember. He observes what comments I'm writing in other people's posts (later tells me about it) and who and what comments are written in my posts. He observes what I'm doing in class and whenever I'm a bit off, he would come to me and talk about if anything is wrong. He also phone calls me a lot. We often talk for 3-4 hours at night. Sometimes just silence, but neither of us cut off the call.
Point to be noted, the way he ignores me and tries to show that he just can't stand me, he never does it with other friends of the group or anyone else. It feels like he has all the enmity with me. And not to mention, he often deliberately makes me angry. We cold-fight a lottt. He picks a quarrel with me and then posts sad stories when i don't talk. I feel like many of his close- friend stories are directed towards me.
So yah I'm very confused. I don't get why he always behaves like this with me.
He ignores me but I'm so confused about his behaviour towards me?
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