Princess Natalie felt that her boyfriend was taking her for granted by forgetting her birthday and she felt that the best thing to do to him was to trample him so that he did not forget it next time and that he did not take anything for granted. The pain he felt as she trampled him helped him learn his lesson the hard way and do things the way she wanted.
Mistress Roxanne wanted this guy to learn that he could not mess with her and get away with it. So the mistress had to force him to do things her way. The mistress was so pissed with him that she painfully crushed and trampled him with her converse sneakers before she ass smothered him and choked him in the process. As she trampled him with the sneakers, she did not care where she smothered.