Looking for a BL where one of the ML gets bullied by someone other then the other ML
Can be bromance like Weak Hero Class 1 and Dogko rewind as well.
Cherry Blossoms After Winter
You Make Me DanceDon't Say NoOxygen
I don't know whether this drama has enough severe bullying for what you are looking for, because there is no physical violence involved. But the way, the class mates make fun of their relationship was a bitter watch to me:
Love Class (season 1)
Night Flight
The Boy Foretold by the Stars
Be My Favorite
The Eighth Sense
Thundercloud Rainstorm (other ML isn't the bully, but he doesn't like him in the beginning)