Han is actually just pretending to be a victim of bullying on campus because he just wants your attention. He wants to have you, your attention, and your love, even though he knows you're just his friend. He hired several people to deliberately bully him

while you and Han were in the library, 3 people came and poured water on Han's head then took his book and walked away laughing

"Hmm, again..." He said in a tone that pretended to be sad