Romance manga where girl reluctantly has a relationship with a violent guy?

Ok so I've been looking for this but cant find it! The manga is about a girl who's pretty much forced into going out with this guy (they're both in highschool). He seems really mean to her and it turns out that he just comes off as scary. Also they were in grade school together (but the girl didn't remember at first) and turns out that he used to tease her but he didn't think that he was teasing her, he thought that he was protecting her. He liked her even in grade school and told his grandmother but she said is the girl didn't have wide hips (for birthing) the girl would not be accepted. That's where the bullying pretty much started. Thanks! Oh btw this manga is completed =)