St. Thomas Aquinas, De Perfectione Vitae Spiritualis :
"Now amongst all relationships the conjugal tie does, more than any other, engross men’s hearts. So that our first parent said (Gen. ii. 24): “A man shall leave father and mother, and shall cleave to his wife.” Hence, they who are aiming at perfection, must, above all things, avoid the bond of marriage, which, in a pre-eminent degree, entangles men in earthly concerns. This is the reason which St. Paul gives for his counsel concerning continence. “He that is without a wife, is solicitous for the things that belong to the Lord, how he may please God. But he that is with a wife, is solicitous for the things of the world, how he may please his wife” (1 Cor. vii. 32).