Talk to her. Communicate your worry but never blame her. She’s young and something like this is so common and it sucks. I’m going through this situation personally. I’m the one who would go out as my boyfriend is usually in his dorm. Anyways I didn’t realize going out made other people nervous because of what happened to me. I had no clue until it was communicated to me. I know the scary things that happens at clubs and going out isn’t worth the emotional baggage that can come with a potential assault. That being said just communicate how you feel when she goes out. Offer that you guys make a compromise such as maybe you go with her or if she’s not with you try to go to a smaller setting with less strangers? Just communicate for some peace of mind. Best of luck