fifteen and dating the wrong guy

My daughter is fifteen she will be sixteen in september and has a boyfriend that has smoked pot and drank before at fourteen he will be fifteen next week.He comes from a family that has alot of personal issues. My daughter has gone out of her way to talk to him and see him behind my back after I grounded her for sneaking out on a secret date without telling me about anything.After this I spoke with her and the so called boyfriend about trust and our rules about dating my daughter the talk went well and I told them they would have to wait to see each other until after the 23rd of JUNE BUT ALREADY they have snuck behind my back to see each other at my own daughters request and now they are saying Ilove you to each other and she has a hickey on her neck!!!