I think you shouldn’t fret about it. VERY likely nothing will happen. In fact, I would encourage this friendship. Teach your daughter a valuable lesson from this. Make sure she is open to many different environments and backgrounds, and can communicate with many different kinds of people. Because if she ever hits rock bottom, she won’t be as sterile and will know what to do. Even if something minor does happen, it’s not the end of your daughter. Children who are overprotected often suffer and encounter way more obstacles later in life. This is a proven fact. They don’t learn to judge and work and think for themselves when they are young and susceptible to knowledge, so overprotective and/or parents who spoil doom their children. Although it is natural to worry, and guidance is needed, over worrying and controlling behaviour towards friends or hobbies or style can permanently handicap them.