One of the distinctive aspects of the Theology of the Body is its beautiful expression of the mutual relations of men and women, a mutuality that originates in and is best expressed by a sexual act which is constituted by self-giving.
It's a position that I am sympathetic to. But Francis Watson's takes dead aim in Agape, Eros, Gender at attempts to establish the sexual act as the grounds for the differences between men and women. He writes:
The belonging together of woman and man is not confined to the sexual relationship, nor is that even its primary expression. The veil is interposed in order to confine eros to his limits, excluding him from the ekklesia, the place in which the belonging-together of man and woman is disclosed, and differentiating him from the agape which is the mode of that belonging together.
As he puts it later, "On what authority is it asserted that man and woman become two and one primarily, or even exclusively, in the sexual act?" The "two and one" refers to their differences, male and female, within the structure of the 'one flesh' union.
We might answer, "On the authority of the created order, which seems to locate the differences between male and female specifically within the marital covenant. "Bone of my bone" is both an assertion of identity and an expression of solidarity.
But Watson anticipates the move, pointing out that inasmuch Jesus is a male, he is so not by virtue of his sexual relations with women (revisionist theories of Mary Magdalene notwithstanding), but by virtue of his relationship with his mother. Writes Watson:
It is true of [Jesus] as of all other males that 'man is now born of woman' (1 Cor. 11.12) and that the belonging-together of man and woman must initially take the form of mother and son. 'Did it ever occur to him to say "yes" to her?' His birth was his 'yes' to Mary, who became his mother as he became her son. His 'yes' to his mother is constitutive of his human existence. To reject this form of the belonging-together of man and woman, to wish to replace it with a relationship centered on sexual union, is indeed to go 'beyond Christianity'. Eros demands the movement 'beyond Christianity' because he cannot endure the limit imposed on him by the divine-human agape.
Which is to say, if you wish to be fully human, men, be nice to your mothers.