Here’s a good word from R. C. Sproul in Intimate Marriage.

In every single marriage that ends in disaster, some stupid decisions were made with respect to God’s regulations. If God’s regulations were followed scrupulously, there would not only be no divorce, there would be no unhappy marriage. To violate the regulations of God is not only an exercise in disobedience, but an exercise in foolishness as well. If you want a happy marriage, the most intelligent thing you can do is submit to God’s regulations. They are designed to promote and protect your full happiness. God carefully planned them. But before the regulations of God can work for our happiness, we have to know what they are. Again, study is required that we may not only know the wisdom of God, but that we may master of it. (In my college classes, the difference between an “A” and a “B” was the difference between knowledge and mastery of the material. [Who wants to be satisfied with a “B” or a “C” or a “D” kind of marriage?] Who wants to be satisfied with anything less than an “A” marriage?)

Confidence in the wisdom of God is closely related to our obedience to Him. A great delusion is contained in the thought, “If I keep His commandments, I will not be happy.” Herein is the fundamental human delusion. There may, of course, be pleasure in disobedience, but there can never be happiness. And happiness in the Biblical sense is more than a warm puppy. When I experience a conflict of interest or conflict of desires between what I want and what God requires, then I know then moral crisis is sin. When I choose my own desire and insult the integrity of God’s wisdom, I, at the same time, reveal myself to be a fool.