Please, I have a question: What is the ruling on a wife sitting on her husband's face?

Sitting on the husband's face may be demeaning to him and contradicts the guardianship (qawamah) that Islam has affirmed for him. If the purpose is enjoyment, it is permissible, except for intercourse during menstruation or in the anus. However, one should refrain from enjoying in this manner, as it contradicts good manners and sound human nature.