This mistress was frustrated with this guy and how he kept taking her round in circles. She had to make him realize that she did not appreciate what he did and it was up to him to do something about. So she turned him into a toilet slave and fed him her poo and her pee. He had never been as degraded as he was by the mistress but he got the message.
This mistress was not comfortable with her man flirting with other girls. She knew it was a recipe for him cheating on her and since she had not cheated on him, she was not going to accept that. So she made him eat her shit so that he learned that cheating on her had a hefty price. And he never did it after that as he did not want to experience her wrath.
When this mistress realized that her boyfriend was not as responsible as she wanted him to be, she knew it was up to her to teach him how responsible she wanted him to be. So she used her shit to shock him and make him fear her as that way, he would be receptive to whatever it was that she wanted to tell him. And it happened that way and they lived happily ever after.