From the encyclical Casti Connubii by Pope Pius XI: 

“How great is the dignity of chaste wedlock, Venerable Brethren.

Matrimonial faith demands that husband and wife be joined in an especially holy and pure love, not as adulterers love each other, but as Christ loved the Church.  This precept the Apostle laid down when he said: “Husbands, love your wives as Christ also loved the Church,” that Church which of a truth He embraced with a boundless love not for the sake of His own advantage, but seeking only the good of His Spouse.  The love, then, of which We are speaking is not that based on the passing lust of the moment, but in the deep attachment of the heart which is expressed in action, since love is proved by deeds.  This outward expression of love in the home demands not only mutual help but must go further; must have as its primary purpose that man and wife help each other day by day in forming and perfecting themselves in the interior life, so that through their partnership in life they may advance ever more and more in virtue, and above all that they may grow in true love toward God and their neighbor. 

This mutual molding of husband and wife, this determined effort to perfect each other, can in a very real sense, as the Roman Catechism teaches, be said to be the chief reason and purpose of matrimony, provided matrimony be looked at not in the restricted sense as instituted for the proper conception and education of the child, but more widely as the blending of life as a whole and the mutual interchange and sharing thereof.

The house built upon a rock, that is to say on mutual conjugal chastity and strengthened by a deliberate and constant union of spirit, will not only never fall away but will never be shaken by adversity.

All these things, however, Venerable Brethren, depend in large measure on the due preparation remote and proximate, of the parties for marriage.  For it cannot be denied that the basis of a happy wedlock, and the ruin of an unhappy one, is prepared and set in the souls of boys and girls during the period of childhood and adolescence.  There is danger that those who before marriage sought in all things what is theirs, who indulged even their impure desires, will be in the married state what they were before, that they will reap that which they have sown; indeed, within the home there will be sadness, lamentation, mutual contempt, strifes, estrangements, weariness of common life, and, worst of all, such parties will find themselves left alone with their own unconquered passions.

Let then, those who are about to enter on married life, approach that state well-disposed and well prepared, so that they will be able, as far as they can, to help each other in sustaining the vicissitudes of life, and yet more in attending to their eternal salvation and in forming the inner man unto the fullness of the age of Christ.”

Excerpt from Chastity: The Angelic Virtue published by Cor Jesu Press

https://corjesupress.com/products/chastity-the-angelic-virtue