Time is a vector that cannot be reversed and has only one direction. He in the current time and space received a call from him in the future time and space, and everything was already doomed.
In fact, it is a boring story where the current male protagonist accidentally answered a call from his future self and accidentally fell in love with his future self. This article is self-inflicted, so please ignore the unscientific stuff.
This article is also known as:
"Why am I so narcissistic"
"Narcissism is a disease and must be cured"
"I knew I would fall in love with you"