The unitive-love nurturing – and procreative purposes of sexual intercourse distinguish us from the animal world. We are not like guppies who cooperate for a moment – the mating female looks for a colorful male with orange spots on his flanks, after mating the male immediately swims off. After birth the baby guppies also immediately swim off. There is no time or need for nurturing or training. There is no need for family. It becomes clear that baby guppies behave as no human infant has ever been known to do. No infant just walked out of the hospital and got a job and started paying rent.
However, it is true that the male guppy and the male human do sometimes behave in very similar ways. Just as the male guppy swims off after mating so does the male human sometimes disappear after mating. The guppy is acting consistently with his nature. The male human is violating his nature.
The human babies cannot swim off and get a job and start paying rent because their brains are not fully developed until age 25. The humans develop more slowly than all other mammals. Humans need loving, nurturing family for almost two decades in order to grow up and become fully human.
Therefore, the unitive-love enhancing dimension of human sexual relations is designed to nurture marriage and strengthen the enduring parenting partnership between the man and the woman who are different but in ways that complement and balance and strengthen each other. One flesh intimacy inside marriage blesses the married lovers and indirectly, their children.
Along the way we are held in by God’s purposes-not fences. Purity does what we are made to do. Purity does not restrict humans but directs humans into a full life of redeemed spontaneity. Purity is doing what we are created to do. Purity wills one thing: “May your kingdom come in us.” Therefore, purity protects us at the center. The Lord’s mastery defeats desires that would take us over. Purity reshapes our desiring life and reorders it for God’s purposes.
The purity of the man, the father, is the only way the woman, the mother, can be sure her children will know their father. The purity of the woman, the mother, is the only way the man, the father, can be sure he is the father of the child.
Without purpose or purity we wander into the bondage and sadism of Fifty Shades Of Grey. Christian hurts Anastasia because he says “I want ultimate control over someone else. It turns me on. It’s the way I am made.” So Christian attempts to invent purposes and meaning for his sexual fantasies.
However, meaning is not arbitrary. I may associate sex with “bondage” but the meaning of sex does not then become physical bondage. Its real meaning goes to its purpose-unitive and procreative. We discover the meaning- we do not create it! All of this requires a training with Jesus, in the Spirit, conducted by parents and Church, for an extended season of life.
Suggested Reading, J. Budziszewski, The Meaning of Sex