In middle ages, many women of wealth had male "tongue" slaves that would "serve" them whenever their husbands were away. The idea of only sitting on a man's face would allow them to experience some pleasure but remain faithful to their husbands.
In ancient Persia, "queening chairs" were crafted to cradle the man's head and neck for support in case he was called to service many women, or if the woman involved needed longer servicing than usual.
Women would sit on the chair and drape their dress over it. There was a hole they'd sit over where the man's face would to be.