Imagine flirting with someone to the point of kissing for other what, a month? More ? You even confessed and the other just ask time to sort out their feeling and when you're waiting, the person you just asked out had already set up a blind date for you. Even though MC is dumb, what he has done was not just rejecting ML feelings but clearly shows he had no intention of being in a relationship with him. Being pissed is the bare minimum
Imagine flirting with someone to the point of kissing for other what, a month? More ? You even confessed and the other just ask time to sort out their feeling and when you're waiting, the person you just asked out had already set up a blind date for you. Even though MC is dumb, what he has done was not just rejecting ML feelings but clearly shows he had no intention of being in a relationship with him. Being pissed is the bare minimum