What did i do to make this guy stop talking to me?

ok well i met this guy on a cruise and it seemed like we hit it off. he lives in Europe and i live in the US, and i know i can't have a relationship with him, but i can still be friends with him. so we talked on fb for a week or two and he keeps saying that he wants to come visit me, we could watch horror movies together, i could go visit him, and then all of a sudden he stops responding to me, keeps just logging off on me, and by a month later it seems like he doesn't even wanna be friends. I mean i made other guy friends on that cruise and i talk to them, and they talk back, we still talk like friends. But he just stopped, and i know he doesn't have a girlfriend, and he's not gay, so what is it? And i didn't offend him, no insults at all, not even a joking "you idiot!" Nothing! i just want know what the hell i did, but i don't know what to do.......Help please?