Using the pretext of showing her how to hold a violin, Jenny's music instructor grasps her arm and touches her unnecessarily. Jenny wants to stop him touching her but is afraid to do so.
The musical instructor's gesture is unnecessary and inappropriate as it creates a hostile learning environment and constitutes sexual harassment. Keep in mind that even professionals or other "respectable" people may err such as anyone else. They may abuse power or gratify their lust at the expense of other people.