The first is that the main couple has very little in common, and know almost nothing about each other. It's not unrealistic for people to date just out of mutual attraction, but it's not much of a basis for a serious relationship, yet at the same time, it seems like one of those shoujo where you're supposed to be reading it hoping they stay together despite the random conflicts that pop up. I'm not really sure then what the point is of reading it when I wouldn't really expect their relationship to last at all.
The other is the introduction of this character that's really obviously supposed to be a rival, but is just really poorly written. He's one of those characters that had a crush on the girl as a little kid, but dealt with it by bullying her. The issue I have with it is that this character hasn't matured at all, and is still following them around being over the top childish, insulting, and obnoxious even in high school, and yet for some reason they never really tell him off or even attempt to make him go away. It's bizarre to read because I can't conceive of anyone just rolling with or taking seriously a character that is constantly calling them childish names, and is just generally obnoxious. The boyfriend even gets jealous of this character, which is just weird to me, when you'd think he'd be getting pissed for him constantly calling his girlfriend names.
