“God makes distinctions between the different kinds of love, and shows that the love of a man and woman is (or should be) the greatest and purest of all loves. For he says, “A man shall leave his father and mother and cleave to his wife” [Gen. 2:24], and the wife does the same, as we see happening around us every day. Now there are three kinds of love: false love, natural love, and married love. False love is that which seeks its own, as a man loves money, possessions, honor, and women taken outside of marriage and against God’s command. Natural love is that between father and child, brother and sister, friend and relative, and similar relationships.
But over and above all these is married love, that is, a bride’s love, which glows like a fire and desires nothing but the husband. She says, “It is you I want, not what is yours: I want neither your silver nor your gold; I want neither. I want only you. I want you in your entirety, or not at all.” All other kinds of love seek something other than the loved one: this kind wants only to have the beloved’s own self completely.” (Luther’s Works, vol. 44, p.8-9).