Princess Serena was horny and this guy did not fuck her as good as she wanted to be fucked. She was still horny when he was done and she was disappointed too. She was not happy about the entire thing and she sought to humiliate him. She did this by forcing him to lick the soles of her feet which she had made sure were stinky before she had him lick them.
Princess Serena did not want to use her high heels to punish her slave. Her feet hurt and she was tired. Using her feet and her high heels required a lot of time as well as a lot of effort, which she did not have. So she took out her belt and used it to whip him and to punish him instead of using her feet. The punishment was equally effective.
Princess Serena did not like how this loser behaved. She tried to tell him to change but he was obstinate. She had to make him change through other means so she humiliated him using her bare feet. She stomped and crushed his face using her feet and she also made him lick her feet. She had fun torturing him and when she was done, she tried again and this time he did what she wanted.