The prime time period for teens to engage in risky behavior is when they are left alone during the after-school hours between 3-6 p.m. Far too many parents of adolescents take a cavalier attitude regarding where their kids are, whom they're with, and what they're doing during this time period. I don't support teens being together on a regular basis in unsupervised homes. Of course, there will be the occasional time where a parent cannot be with them on a given day, due to a last minute change in priorities or an emergency. But teens' regularly hanging out in homes without a parent present is unhealthy and risky business.

You have explained your opinions and your values to your daughter regarding this issue. You and she may respectfully disagree on this topic, but you need to make your parenting decisions based on what is best for your child. I think you have made your decisions in a most reasonable manner. Parenting isn't a popularity contest and we should expect some disagreement, anger, and resentment from our maturing, independent-minded teens. As for your "ratting out" this girlfriend of your daughter who had her parents believing that she was with her friends in a parentally-supervised home, this girl is learning the consequences of lying. You revealed this information in the course of a regular conversation and shouldn't feel guilty that his girl's lie was discovered as a result of this discussion.