Why does this man still want to mentally torture me?

Long story short, I started talking to a man, he is from the same city where I am from, everything was going very well, we video called each other daily until one day he stopped feeling interest, and I noticed the coldness and distance , so I also walked away, first when we started talking he told me that he wanted a serious relationship, and I told him that I did too, we were on the same page, then the distance happened, he wrote to me when he wanted and when I responded, he ignored my answers, absolutely all the messages were ignored, so I blocked him from WhatsApp, but not from Facebook, and 1 day ago I received a friend request from a stranger, I accepted it and that person wrote me something extremely random, I finally find out that he was friends of the guy I used to talk, that happened the day I blocked him, I'm already tired his mental games, how can I make him leave me alone? He obviously don’t like me at all.
What does he want with all this?
Why does this man still want to mentally torture me?
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