"It is good, very good, in the Creator's eyes.  And this love which God blesses is intended to be fruitful and to be realized in the common work of watching over creation: "and God blessed them, and God said to them: 'Be fruitful and multiply, and fill the earth and subdue it.'" (CCC 1604)

Men and women considering marriage yearn for certain things. They want to be accepted unconditionally by each other. They want their marriage to be filled with love and happiness. They want a family. In short, they want their marriage to be a source of joy and fulfillment their whole life long.
 
God’s plan for marriage, from the time he first created human beings as male and female, has always included all this and more. The desire and ability of a man and woman to form a lasting bond of love and life in marriage are written into their nature.

In the Rite of Marriage (1969) a man and woman are asked if they will love one another faithfully and totally—in short, if they will love as God loves. “Have you come here freely and without reservation to give yourselves to each other in marriage?” asks the bishop, priest, or deacon. “Will you love and honor each other as man and wife for the rest of your lives? Will you accept children lovingly from God, and bring them up according to the law of Christ and his Church?” These are different ways of asking the same basic question: Are you ready to accept this person, and all that may come from your union, completely and forever?

The spouses seal their love and commitment through their sexual union. Many today find it difficult to understand how profound and meaningful this union is, how it embodies these promises of marriage. Our culture often presents sex as merely recreational, not as a deeply personal or even important encounter between spouses. In this view, being responsible about sex simply means limiting its consequences—avoiding disease and using contraceptives to prevent pregnancy.

This cultural view is impoverished, even sad. It fails to account for the true needs and deepest desires of men and women. Living in accord with this view has caused much loneliness and many broken hearts.

God’s plan for married life and love is far richer and more fulfilling. Here sexuality is the source of a joy and pleasure that helps the spouses give themselves to each other completely and for their entire lives.

What does the Church teach about married love?

Marriage is more than a civil contract; it is a lifelong covenant of love between a man and a woman. It is an intimate partnership in which husbands and wives learn to give and receive love unselfishly, and then teach their children to do so as well. Christian marriage in particular is a “great mystery,” a sign of the love between Christ and his Church (Eph 5:32).

Married love is powerfully embodied in the spouses’ sexual relationship, when they most fully express what it means to become “one body” (Gn 2:24) or “one flesh” (Mk 10:8, Mt 19:6). The Church teaches that the sexual union of husband and wife is meant to express the full meaning of love, its power to bind a couple together and its openness to new life. When Scripture portrays God creating mankind “in his image” (Gn 1:27), it treats the union of man and woman as joining two persons equal in human dignity (“This one, at last, is bone of my bones / and flesh of my flesh,” Gn 2:23), and as being open to the blessing of children (“Be fertile and multiply,” Gn 1:28).
 

 More Resources on the Beauty of Marriage

The U.S. Conference of Catholic Bishops: