Why did my ex start to follow my cousins?

He’s not even an ex he was a guy I slept with. He experienced jealousy and possessiveness when we were together. I found out 7 months later he’s followed my cousins. He doesn’t engage with their posts or anything he just followed them. He has a girlfriend and everything I don’t understand why he would do this tbh.

Why did my ex start to follow my cousins?
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