John Chrysostom (attributed)

But, as when you see one much pursuing the acquaintance of physicians, you know that he is sick, so, when you see either man or woman enquiring concerning divorce, know that that man is lustful and that woman unchaste. For chastity has pleasure in wedlock, but desire is tormented as though under a slavish bondage therein. And knowing that they had no sufficient cause to allege for their putting away their wives, save their own lewdness, they feigned many divers causes. They feared to ask Him for what cause, lest they should be tied down within the limits of fixed and certain causes; and therefore they asked if it were lawful for every cause; for they knew that appetite knows no limits, and cannot hold itself within the bounds of one marriage, but the more it is indulged the more it is kindled.