I've watched 10 episodes. It's common for girls to idealize handsome older boys but I totally agree that the way the story is told is very strange. I just cannot accept the male lead's behavior. Why would a guy who is supposedly always busy working to make a living go to all the trouble to pretend to be her brother? Did he do anything to feel he owes anything to the girl?
Then at every encounter they ever have he never even says "Hi". He'll say something cheesy or even start flirting with her in front of her brother/his friends. At the same time, he is protrayed as Mister Perfect. Give this guy a different appearance and people will say he is a pervert.
It's their third meeting and he gives her a bottle of milk by pressing against her cheek when he approaches her from behind.
Also he insists she should spend the morning with him doing homework. Then that essay he wrote for her. Why was that necessary?
People of different ages may become friends, but this relationship needs some foundation, like shared interest or a desired to protect the weak one. Is she ignored by her family or bullied by classmates? There is absolutely for him to be so involved in her life and her affairs at this stage. I would definitely warn teenagers against such kinds of stories.