It sounds like the person who has an issue in this situation is you. There is nothing sexual about a 15-year-old girl in a towel in her own home. Asking her to change her attire and her behavior to accommodate you-- because you are having a reaction to her body-- is unfair and shaming. Most people do walk around their houses in their bath towels when they are getting ready and no one views it as sexual. Asking a girl (or a woman) to change her attire because a man feels uncomfortable just doesn't seem right. It's her body and her house. i see nothing wrong with her behavior. She is not trying to simply "get her way." It sounds like she is reacting to the fact that suddenly some guy her mom picked gets to dictate what she can wear in her own house. The home shouldn't be a place where a young woman's body gets to be policed and sexualied and shamed. I certainly walked around my house in a towel when I was a teenager and getting ready in the morning. It would have been detrimental to my self-worth and sense of safety if an adult male had made a big deal out of my body and insisted I wear knee-length/full-sleeve garments at all times to accommodate them.