22 Nay, that mutual familiar intercourse between the spouses themselves, if the blessing of conjugal faith is to shine with becoming splendor, must be distinguished by chastity so that husband and wife bear themselves in all things with the law of God and of nature, and endeavor always to follow the will of their most wise and holy Creator with the greatest reverence toward the work of God.
Source: Casti Connubii (Vatican.va)