Of course, lust is distinct from erotic desire. Aquinas understood lust as a virtue contrary to chastity. Indeed, your advice to a husband to “slobber away” in its dismissal of reason forgets Aquinas’ observation that “[t]he more necessary a thing is, the more it behooves one to observe the order of reason in its regard; wherefore the more sinful it becomes if the order of reason be forsaken.”(1)
“Lust is disordered desire for or inordinate enjoyment of sexual pleasure. Sexual pleasure is morally disordered when sought for itself, isolated from its procreative and unitive purposes.” (2) To lust, therefore, even after one’s own wife, and to contemplate only the venereal pleasure to be had is exactly what the Church is talking about. That contraception would be absent is immaterial to the moral question. Since the primary directive in the man “slobbering away” is the acquisition of his own selfish pleasure, the procreative dimension of the act is rendered irrelevant and the unitive dimension utterly destroyed.
There is a further question of propriety involved in allowing anyone to be overcome by their own sexual impulses at any time. “Slobbering away,” like an animal, weakens the moral faculty since it allows hedonistic abandon. Though only limited to one’s spouse, such a vice, like all vices left unchecked, will fester, grow rampant and spill outside of the marital relationship.
Finally, to allow for lust within marriage is a Manichean conception of the sacrament. A man’s wife is more than simply a concession to his inability to control himself. The marital act itself is meant to be an image of the holy communion of Persons that is the Trinity and a reaffirmation of the marriage vows. Approaching the marriage bed “slobbering away” is about as misguided as doing the same before the Eucharist.
(1) Aquinas, Thomas. Summa Theologica. 1920. New Advent. Trans. Fathers of the English Dominican Province. Online Edition, 2006. Secunda Secundae Partis, Q. 153, Art. 3. Available online at:
newadvent.org/summa/3153.htm
(2) Catechism of the Catholic Church. Vatican City: Libreria Editrice Vaticana, 1993. ¶ 2351. Available online at:
vatican.va/archive/ENG0015/__P85.HTM