After receiving an invitation to meet my long-time friend's girlfriend, I quickly went to his house to congratulate him. His girlfriend was a beautiful, fair-skinned girl with slender legs. That night I stayed over at his house, and in the middle of the night, I woke up needing to use the bathroom. As I opened the bathroom door, I was taken aback by the sight of my friend's girlfriend passionately masturbating. It turned out she wanted to have sex but was denied by him, so she resorted to taking care of her needs here. When I caught her, she was very embarrassed, but once outside, her attitude completely changed. The look in her eyes seemed to express a strong desire for me to help her relieve the craving in her body. That night, we did something wrong with my best friend.