Why did my ex unfollow me on Instagram 2 weeks after the breakup, & then refollow me after I said hello to him?

My ex and I broke up a month ago. It was mutual because there was a strain but he wanted it more than I did at the time. A month later I’m doing really well but he’s been so weird. He started posting on Instagram LOADS & putting up Snapchat stories and insta stories nearly every day, which is very unlike him. Then I noticed one day after I posted a nice selfie, he unfollowed me on Instagram. A couple of days later I noticed he was starting to watch my insta stories though, as I’m on public. And yesterday I passed him for the first time in a month and gave him a proper hello & he then later on re followed me on Instagram.. seems like he's acting a small bit childish but I don’t know? Everyone’s saying he’s now hurting from the breakup and that it hit him later than it hit me. I’d ignored messages from him & went really quiet & wasn’t liking his insta photos in return, as I needed time to heal. It just looks like he’s constantly looking for attention? I don’t know? Like I’d love to one day get back with him but only if he were to grow up, & I don’t know if the way he’s behaving is because he’s over me or because he’s lost? Please help!
Why did my ex unfollow me on Instagram 2 weeks after the breakup, & then refollow me after I said hello to him?
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