Ugh this is gonna be so embarassing, but i need help remembering the title of this korean ...

Ugh this is gonna be so embarassing, but i need help remembering the title of this korean bl manhwa. It's a spin-off, the top is currently a college student and he meets his high school teacher at the wedding of his stepsister, whom he had a crush on. He found out that the teacher was gay and he thought him and the sister's husband had an affair or something. He hated the teacher for a while cause he was very depressed and also an alcoholic, but then he fell for him and you know what happens after.

Anyways it's a really popular work, i read it once before but I wanted to reread again once the official translations got completely uploaded and now I've forgotten the name. Please help meeee (desperate).