stepbro•3•'s Things

i’ve been looking for this manga for 2 days and i cannot find it it’s a high school friends to lovers where the friend (call him a) is helping more introverted friend branch out while being in love with him. a’s friend meets a girl and spends more time with her, and there’s a scene where a’s friend and the girl r in the library together and a goes into a classroom and is like “i’m sure they’re gonna get together” and he cries but then his friend comes to find him and confesses. pls i cannot remember for the life of me what it’s called, and i cant remember if it was a full manga, a side story, or a one shot. help!