Obsessed with older boys

Hello. Our DD is 13 and she is becoming more and more obsessed with boys. She has lost friends at school because she claims to be with her friends boyfriends, she writes their names all over her notebooks and her arms. She is now attending the boys and girls club and is obsessed with a 17 year old volunteer who complained to the director that she is going around saying they are boyfriend and girlfriend and writing it all over everything. She will jump at the chance to sneak around with any boy who shows the least bit of interest in her. We are at a total loss as to what to do with her. We had to pull her out of the last summer program she was in because of the same thing. We are discussing this in therapy now. But we just don't trust her alone for any length of time. My husband had to change his hours at work so he could be home with her after school so she wasn't unsupervised. We are constantly worried that she'll make a false allegation or end up pregnant we just don't know what to do. The last resort seems to extreme but we may have to put an alarm system on the house and a surveillance camera to make sure she isn't sneaking out or inviting someone in. She only does good with younger kids but we can't find a program that would accept a teen that she would be the only teen there.