Boys must separate from "mother" to form a gender identity. This causes boys to form a set of defenses against abandonment by "mother" and to form a strongly separate sense of self.
Because this separation of "mother" and boy comes before the ability to express complex emotional responses in words, a man often cannot talk comfortably about what his feelings mean to him. Emotions are dangerous and make him feel vulnerable. Reason and logic provide protection.
William Pollack in his book Real Boys: Rescuing Our Sons From the Myths of Boyhood, writes that boys are expected to detach or pull away from their mothers before they should.
A man then spends his life torn between a desire for close and intimate relationships with women and a defense against any relationship where intimacy and intensity are strong enough to mimic the strength of the relationship with his mother.
The girl child has less need to separate from "mother." Thus, she becomes a woman who needs relationships. Relationships offer safety while isolation offers threats.