So, what I'm thinking is that the two main characters are in a private high school. The girl has always been a rather good student, always had high scores, involved in extra curricular, etc... etc... Although being allowed to date, she never was very interested in any of the boys at her school. Then one day a boy and his family move in next door/across the street/down the hall. Right away rumors begin to fly around the school about him, spreading even faster due to him getting into a fight before the end of his first day.
From there on the girl can try to befriend him, or get assigned to tutor him, or something else that would cause them to interact more. Or the boy can begin to chase after her, feeling attracted to her from the start.
I'm quite flexible with any ideas, and this can go anywhere from van to nc-e as far as I'm concerned.