@Potatosan~ The ML is not confirmed yet, but if I think black hair is not the ML, it's because he is never there at critical moments. He likes the FL just after she stayed at his place for 3 weeks, but the author didn't develop their relationship further than that. Whereas for the blond one, the FL didn't even stay for more than 3 days in his place, yet she already has a different opinion about him, and the author dedicated several chapters to develop that.