Proverbs 5:21-23 lists three reasons for us to be faithful to our spouse: God is watching, wickedness ensares, and we could die (physically or spiritually).
But the real reason we maintain moral purity and practice our love at home is because of God. In verse 21 Solomon provides a strong theological rationale for morality: God sees everything we do. Even if our marriages are not always as satisfying as we would like for them to be, we still maintain faithfulness because God is the author of our lives and marriages. The honor we hold for God invites his ethic into our relationship.
Marriage is not just husband and wife. Marriage is husband, wife and God. Malachi says that "the Lord God made them one. In flesh and spirit they are his ... So guard yourself in your spirit, and do not break faith with the wife of your youth." (Malachi 2:15).
If we truly honor God we will likewise honor our spouses. The love we have for God leads to a deep respect for our husband or wife. While we experience pleasure in the physical relationship together, we can never view our spouse as an object of pleasure. He or she is our covenant partner.
The respect we practice ensures that we will treat our partner’s feelings and body with dignity and honor. We will never belittle them or hurt them, and we will certainly not step out on them. The basis for treating our spouse with this level of dignity is not simply that we don’t want to get caught and embarrassed, but that we honor God.
This is part of a larger article which you can read here: A Blessed Fountain, based on Proverbs 5:15-23.