i'm actually confused too but based on what i understood he knows that the MC like him since childhood but he just like meeh i just wanna be friends with you and acted like he didn't know and when they were going to be college student he asked his brother for help i think to make the MC unlike him(not sure about this one it was super confusing) and when he can see that the MC is getting well with his brother he then like confessed with the MC and like took it back then said it again(this part is also confusing) but overall in my opinion he did not have the right to play the MC like that so that's why Maru is a sickass bastard. Correct me if i'm wrong cuz the story line was really confusing
so basically based on what I understood Maru is fcking sick bastard thats all thank u