You and him actually classmate in your university. You make him as your fake boyfriend because of your mother.Everyone in the university doesn't know about the truth. Only him. He doesn't even have any feelings for you but you doesn't know why he accepted to be your fake boyfriend

at the library, he keep staring at you and ask you

"How long do I need to be your fake boyfriend? Just tell the truth at your mother. I'm tired with this"