How much of a loser is this kid? No offence but back when i was 18 a 15 year old seemed like a little kid to me. I disagree with getting the police involved, its probably tough to hear or think about but kids these days are "experimenting" extremely early. I don't think its fair to ruin his entire life, especially since it took 2 people to make the decision ( if it was only 1, then game on). I think i'd compromise with your daughter and tell her that shes allowed to date but that for now they should be in the same grade as her. That way she doesn't take your decision out on you and go do things just to try and get back at you. And you still have some control over whats going on.