Any parent of a girl in the circumstances you describe would be very wrong to push for prosecution, assuming the girl was just as willing.
If it did get to court (very unlikely) the girl would have to stand in the dock and give evidence. Her reputation would be shredded by the defence and it would be more harrowing than the relationship itself.
This wouldn't happen in a week - it would happen months after giving statements to the police, possibly psychiatric and social services reports, reports from her school teachers and muck raking evidence from her school friends.
This at a time when she should be studying for her exams and planning her future.
Really, the parents should help the girl not view herself as a victim, but come to terms with her feelings so she deal with the break up of her first proper relationship and get on with her life.
I sincerely hope this is the option the parents take. It is incredibly difficult to come to terms with the fact that your child is sexually active but now is the time to make sure she understands how to look after herself both emotionally and physically, and fully understands contraception and sexual health.