No one, with the exception of Bill Clinton and other homosexual supporters, teaches what Luther taught on marriage:
"Be a sinner, and let your sins be strong, but let your trust in Christ be stronger, and rejoice in Christ who is the victor over sin, death, and the world. We will commit sins while we are here, for this life is not a place where justice resides... No sin can separate us from Him, even if we were to kill or commit adultery thousands of times each day." from 'Let Your Sins Be Strong, 'The Wittenberg Project;' translated by Erika Flores, from Dr. Martin Luther's Saemmtliche Schriften, Letter No. 99, 1 Aug. 1521. - Cf. Also Denifle’s Luther et Lutheranisme, Etude Faite d’apres les sources. Translation by J. Paquier (Paris, A. Picard, 1912-13), Vol. II, pg. 404).
“If the husband is unwilling, there is another who is; if the wife is unwilling, then let the maid come..." Luther, On Married Life
"Suppose I should counsel the wife of an impotent man, with his consent, to give herself to another, say her husband’s brother, but to keep this marriage secret and to ascribe the children to the so-called putative father. The question is: Is such a woman in a saved state? I answer, certainly.” Babylonian Captivity of the Church
In a letter to the Saxon Chancellor Gregor Brück, Luther stated that he could not "forbid a person to marry several wives, for it does not contradict Scripture." ("Ego sane fateor, me non posse prohibere, si quis plures velit uxores ducere, nec repugnat sacris literis.") Letter to the Chancellor Gregor Brück, January 13, 1524, De Wette 2:459.
As to divorce, it is still a debatable question whether it is allowable. For my part I prefer bigamy to it.” From On Marriage
From a strict Lutheran point of view, Bill Clinton was an excellent Lutheran.