The primordial story of man and woman hints that, despite all the dangers that accompany the humanization of sexuality, it is complementarity — the heterosexual difference — and not just doubleness that may point the way to human flourishing altogether. Conscious love of the complementary other draws the soul outward and upward; in procreation, love, mindful of mortality, overflows generously into creativity, the child unifying the parents as sex or romance alone never can, and the desire to give not only life but a good way of life to their children opens both man and woman towards a concern for the true, the good, and the holy. Parental love of children may be the beginning of sanctification of life. Perhaps that is what God was thinking when He said that it is not good for the human being — neither for man or woman — to be alone. Perhaps this is why “male and female created He them”.
(Leon R. Kass, The Beginning of Wisdom, pp. 121-122)