I said to to my psychologist once "a womans word has no value" when she says yes or she says that she wants to be with you that reflects what she is feeling in that moment, the concept of promise, commitment or duty is foreing to their minds, they see no value or no need to keep a promise, is all about how their are feeling at the moment and to get the best deal.

Ps: the psychologist agreed with me and she was a woman.