Deuteronomy 24:5

The immunity here given has for its object the awakening of that mutual love which may preserve the conjugal fidelity of husband and wife; for there is danger lest, if a husband departs from his wife immediately after marriage, the bride, before she has become thoroughly accustomed to him, should be too prone to fall in love with some one else. A similar danger affects the husband; for in war, and other expeditions, many things occur which tempt men to sin. God, therefore, would have the love of husband and wife fostered by their association for a whole year, that thus mutual confidence may be established between them, and they may afterwards continually beware of all incontinency.

But that God should permit a bride to enjoy herself with her husband, affords no trifling proof of His indulgence. Assuredly, it cannot be but that the lust of the flesh must affect the connection of husband and wife with some amount of sin; yet God not only pardons it, but covers it with the veil of holy matrimony, lest that which is sinful in itself should be so imputed; nay, He spontaneously allows them to enjoy themselves. With this injunction corresponds what Paul says,

“Let the husband render unto his wife due benevolence: and likewise also the wife unto the husband. Defraud ye not one the other, except it be with consent for a time, that ye may give yourselves to fasting and prayer.” (1 Corinthians 7:3.)