Just now I was listening for a second time to the talk Jules gave yesterday morning in Steubenville on von Hildebrand's distinction between the primary "meaning of marriage", i.e. love, and the primary "end of marriage", i.e. children. (I can't think of anything I'd rather do than listen to my beloved talk about marriage.)
Specifically, he tries to show that not only does this distinction not (as some critics charge) undercut the Church's teaching on the inseparability of sex and pro-creation, it deepens and enriches our grasp of that teaching, by drawing out and emphasizing the personal structure of conjugal relations.
Spouses don't use each other to produce children. God doesn't use couples to propagate the human race. Rather, the spouse give themselves to each other in love, and they receive their children as gifts—the superabundant fruit of their love for one another.
There was some discussion, too, about the impiety involved in contraception—the separating of what God has joined, namely sex and procreation.
A question came up afterwards on that point. One participant wanted to point out that while sex can't be validly separated from procreation, it can, it seems, be validly separated from love. She gave the example of a couple who are in an arranged marriage, where there is as yet no experience of spousal love. Can they not validly engage in sex, and therefore can we not say that it is possible to (legitimately) have sex even apart from love?
Several good points were made in reply, both by Jules and by other participants. I won't rehash them here. But this morning I noticed a comment by someone following the talk by livestream. He said this:
In fact, it is loving to love one's spouse, even in an arranged marriage where there is no feeling of love, in an intrinsically good martial act (open to life, self-giving, etc). Spousal love still exists, even apart from the feeling of affection...
I have some things to say in reply to this.
First, it is of course morally valid for a married couple who are not in love with each other to have sex. Sex in such cases can even be a genuine act of love, in the sense that it is consciously intended to "do good for" the spouse, to honor the objective relation between them, to draw closer to each other, etc.
BUT, a few things should be noted.
1) It would not be true to say that because the marriage is valid and objectively open to life, sex within it is ipso facto an act of love. In fact, sex within marriage can be unloving, both objectively and subjectively.
2) It's not easy for sex to be an act of love absent the conscious experience of love. (This is one reason why all Christians should reject the practice of arranged marriages.) It is much easier for the sex in such cases to be selfish, utilitarian, perfunctory, or merely pleasure-seeking. Wives in loveless marriages often feel (and are) not loved, but used by their husbands' sexual advances. They feel disregarded as persons, reduced to their function as wife. The result is alienation, not intimacy. And it's not only wives. I know of cases of couples struggle with infertility, where the husband has felt used by his wife. "I'm ovulating. We need to have sex right now!"
3) Even the best cases of loveless sex—I mean cases where the sex is genuinely motivated by a desire for union and an intention to do good for the other—fall short of the ideal. And by "ideal" here I don't mean "perfection," but something more like "what God intended in the design of conjugal love." The conjugal act is meant to be a union of reciprocal love, felt love. When it's not, something vital is missing, and usually the spouses suffer the lack.
We shouldn't imagine anything else.