Princess Serena did not like how her boyfriend did not take good care of his mouth. She was pissed that he had not taken her advice into consideration and she had to do something about it. The mistress used her sneakers to trample him and by the time she was done with him, he had seen what she was telling him and he agreed to do things her way to avoid future issues.
Princess Serena had always been there for her friend. But when she needed him, he was not there for her. When he needed her again and asked her for assistance, she did not give it to her. Instead, she trampled him with her sneakers and made sure he learned his lesson. She told him he had disappointed her when she needed him and she was also going to disappoint him.
Princess Serena asked her slave to do something for her, but he thought she was joking. When she came back and found he had not done it, she was pissed off and punished him for it. She did not talk to him. She just trampled him as punishment. She used both her bare feet as well as her shoes to do it. She even jumped on him to make it more painful.