You talk a lot about your daughter's choices but are neglecting any mention of how your or her fathers role as a parent has been. Are you and her dad together? Has she witnessed similar behavior in you or her dad? Has she witnessed this guys behavior in her dad, or you dating guys and behaving in a similar fashion?
Kids know and learn from what they see and experience. Please know that I do not condemn you if you answer yes to any of the questions I asked. I'm divorced, I have three kids, and I KNOW my ex has a horrid dating history, even after we divorced, so I don't expect my kids to make the best dating choices. That's where I'm going to need to step up as a responsible parent and tell them, no, this isn't going to fly. They will break up with that person. If they don't, and I find out about it, they will not be on facebook anymore. If they're sneaking out, or lying about where they're going, they can kiss any freedom they have goodbye for a while. They'll probably hate me, but that relationship will not happen, and eventually they'll thank me.