Nobody here can answer your question about why he’s ghosted you. But yes, that’s what he’s doing. He’s pulled away, and now you have to move on, too. In general, though, you should probably spend less time agonizing about the actions of someone who was a long-distance pen pal. And his “joke” about beating his ex isn’t just “strange” — it’s alarming and a huge, waving red flag.
I told him that it was appalling and he had the nerve to put it on his culture, saying “you would not understand, my dad is Arabic, it is a joke you know, nothing big, just a broken nose, ha ha”. I told him he was insane and he said “c’mon, I am just kidding” but the fact that would even cross his mind, in any way, is strange enough to not make me too worried about the ghosting. In any case, thank you to all here and I have noted all your advice, including the part about not taking casual encounters or people living in other places (hard to do as my job requires me to travel a lot) too seriously.