Lady Cary loves to dominate guys and especially sexually. For her, it is not penetrative domination but rather, one where she dominates them by teasing them and then denying them. She makes them think that she is into them but she is really not and is only into humiliating and dominating them for her own fun. The guy never saw it coming and he had to jerk off to satisfy himself after she left him high and dry.
Lady Cary loves to tease and she did so to her ex. The mistress did it because she felt that she knew his buttons and she could press them anytime she wanted. She also did it because she knew that he had a thing for her and he wanted her. The mistress did it to pass time, make fun of him and also to have fun at his expense. But she did not want to sleep with him.