It doesn't come as the result of other acts of charity within a marriage; it is a cause of them
Consider: when the subject of marital sex comes up, it’s often treated like a secondary feature of the true love of married people, behind what is thought “more important” (“romance,” “communication,” “service”). We tell ourselves that these things, done well, lead to a fulfilling sex life, but that a great sex life cannot come before them. Marriage counselors routinely encourage couples to focus on what they do out of the bedroom in order to strengthen what they do in the bedroom.
I’ll argue that the truth is quite the opposite, that sex is the food of marriage, and the principle source of energy and direction for all of the rest of it. Sex does not come as the result of other acts of charity within a marriage, it is the cause of them.
Being an attentive spouse, one who is energized to participate fully in the responsibilities of home life, who feels compelled and enamored so as to become a complete servant of love, is the product of the intimate union that is only whole and complete in the marriage bed. This is because of what sex is. With one exception, sex is the only way on this side of paradise that two humans can be substantially united to one another. The word substantial here is technical; it means the wholeness of the human substance — the soul and the body united — a unity that makes the human what it is. The exception to this, of course, is the reception of the Eucharist in which we are substantially united to Christ in his body, blood, soul, and divinity; and true though it is we need to receive the Eucharist only once a week, there are countless benefits to receiving the Lord as often as possible for He is not only the summit, but the source of our Christian life.
Sex is this in marriage; it is the summit and the source and driving power of all acts of charity in a marriage because it is the substantial communication of two humans who become literally one organism. The spouses pull each other out of themselves in the most powerful and raw experience of delight possible (they literally fall outside of themselves with pleasure, for the word ecstasy comes from the Greek ex-stasis which means “to stand outside”). In doing this they find themselves more whole and complete within each other.
This delightful life is fun, but it is no game; any lover worth his salt knows this. The writhing form of his beloved under his touch requires concentration and dedication, sensitivity to her needs, humility in face of her beauty, vulnerability to receive what is given in the form of delight, endurance (both physical and mental), thoughtfulness, practice, anticipation, perseverance, humor, tact, joy, laughter, courage, patience and communication, just to name a few.
I mean by this no metaphor; I am talking about the physical act in the bedroom whose excellence is manifest especially in the physiological response of both parties.
Seeing sex in this way, as it truly is, shows it as the training ground for every other virtue that can be expressed in any other activity within a marriage, be it helping with chores, listening to a spouse, being vulnerable, forgiving, etc. Marital sex is the supreme and most perfect act whereby a husband and wife demonstrate that the very existence of the other is good; that from the depths of her soul to the tips of his toes each sees the other as cause of delight beyond compare. If sex is not this, then it is not being done well.
Marriage finds the source of its charity in this profound union whereby the boundaries between two beings dissolve without any loss of individual identity. This counters the current idea that sex is “more” than physical. Sex is more than physical, but that is like saying that the crucifixion is more than physical — yes, but also no, for without the crucifixion we get none of its spiritual goods.
What we need in marriages is better sex, and a focus on it — we need to perfect the act of sex, first, so to perfect marriage; we need to learn to delight in delight, and to let the physical act of love-making pierce us so we can pour ourselves out unreservedly, as Christ did from the cross, and let the power of the sacrament of marriage flow into our homes and family lives.
Sex is the good gift of spouses to one another. It feeds, sustains, uplifts, and directs all of a couple’s charity to each other and to the world. Sex starts a marriage, sex sustains a marriage, sex leads a marriage, in the degree that it is perfected, to the perfection of charity in all other acts.
[Headline edited for clarity – Ed]