How do you help someone who's scared of a woman?

Everyone has that friend. You know the one I'm talking about. The one who's had that same girlfriend for a few years and always does what she tells him. Completely scared shitless. On a side note, Why do women do this? Honestly. and also this happens vice versa. Where the woman is completely scared shitless of the man. Why do men do this? One thing I have noticed about this for women is as follows. Girls who are brought up in a male dominant atmosphere become dominant themselves. Perhaps they feel the necessity to not be like their mothers.