The manga I'm looking for was a shounen Ai if I remember correctly. I also believe it was on Tapas, if not still, but i couldn't find it and have no clue what the name was.

The plot was something like this:
The main lead (who had lighter color hair) ran into some rude guy on the way to class who spills a sandwich on the mls shirt ruining it. He later finds out after class that this guy was some terrible ex of his friends who was kinda toxic. Then his job by his friend to help him out is to make his friend's ex fall in love with him and then dump him and break his heart to teach him a lesson.
I think you also figure out that the ex is not open about liking guys too. Also the ex tends to be VERY protective and at one point beats someone up.

I don't remember finishing it and would really like to. If someone could help me out i would appreciate it so much 🙂