1Cor 7:2

“You have given up your wife, to whom you are bound. This is a big step you have taken. You are not abusing her, you say, but claiming that you can be chaste and live more purely. But look how your poor wife is being destroyed as a result, because she is unable to endure your purity! You should sleep with your wife, not for your sake but for hers.”

“He added immediately, "Nevertheless, to avoid fornication, let every man have his own wife". and come together again, that Satan tempt you not for your incontinency. But I speak this by permission, and not of commandment."”

“There would be no adulteries, and debaucheries, and prostitution of women, if it were known to all, that whatever is sought beyond the desire of procreation is condemned by God. Nor would necessity compel a woman to dishonour her modesty, to seek for herself a most disgraceful mode of sustenance; since the males also would restrain their lust, and the pious and religious contributions of the rich would succour the destitute.”

“People who want to be promiscuous argue that God commanded us to have sexual relations, so that the earth would be filled with human beings. But God is quite capable of making humans out of the earth, as he did at the beginning, so this is no excuse.”

“He speaks about both sides. For it may happen that the husband loves chastity, but the wife does not, or vice versa. With the words "to avoid fornication" he urges restraint. For if marriage is permitted to avoid fornication, then those joined in marriage ought not to have relations with one another without any moderation, but rather chastely.”

“Against the vowing of widowed continence it is objected: 1 Corinthians 7: On account of fornication let each man have his own wife, and each woman her own husband: but that is not a counsel, since it is not a work of perfection nor of supererogation: therefore it is a precept: therefore whoever vows continence acts against this precept.”

“To that which is objected from the word of the Apostle, who says: On account of fornication, let each man have his own wife; it must be said that the following text determines this: But I say this by way of concession, not by way of command. Whence the Gloss on the aforementioned word: "The Apostle says this in order to exclude fornication, not to close the way to those striving toward a better life." And because the Apostle had said: Let each man have his own wife, and each woman her own husband, and come together again; namely, lest he should seem to have said this by way of precept, he adds: But I say this by way of concession, not by way of command. And therefore he does not sin who acts otherwise, that is, who practices continence; rather, he who acts thus sins, because there is some fault there, but a light one.”

“Then when he says, But because of fornication, he shows what is necessary in this matter: first, as to contracting marriage; secondly, as to the use of the matrimony once contracted (v. 3). In regard to the first it should be noted that the act of the generative power is ordained to the conservation of the species by the generation of offspring. And because the woman was given to the man as a helper in generation, the first need for touching a woman is for the procreation of children. Hence it says in Genesis (1:27): "Male and female he created them. And God blessed them, and God said to them, 'Be fruitful and multiply, and fill the earth.'" But this need was directed to the formation of the human race, as long as there was need for the people of God to be multiplied by succession according to the flesh. But the Apostle, considering that the human race had now multiplied and that the people of God were now increased not by fleshly propagation but by the generation which is from water the Holy Spirit, as it says in Jn (3:5), he passed over this necessity whereby marriage had been originally instituted as a function of nature, and proposed a second necessity according to which it was instituted as a remedy for sin. For since carnal desire remains alive in believers even after baptism, although it does not rule, it impels men especially toward venereal acts on account of the vehemence of their pleasure. And because it requires greater virtue to conquer this desire entirely than can belong to men, according to Matthew (19:11): "Not all men can receive this saying", it is necessary that this desire be in part yielded to and in part mastered. This, indeed, happens when the act of generation is ordained by reason and man is not totally mastered by the desire, but the desire is rather subjected to reason. Natural reason teaches that man use the act of generation according as it is suitable for generation and education of children. But in brute animals it is found that in certain species the female alone is not sufficient for the training of the offspring, but the male takes care of the offspring with the female. For this it is required that the male recognize its offspring. Therefore, in all such animals, as doves, pigeons and the like, solicitude for the training of offspring is inspired by nature. Wherefore, in such animals coition is not random and indiscriminate, but a definite male is joined to a definite female, not one to another promiscuously, as happens in dogs and such animals, in which the female alone takes care of the offspring. But above all in the human species, the male is required for the education of the offspring, which are attended to not only regarding bodily nourishment, but to a greater degree regarding the nourishment of the soul, as it says in Hebrews (12:9): "We have had earthly fathers to discipline us and we respected them." And consequently, natural reason dictates that in the human species coition is not random and uncertain, but is by a definite man to a definite female, who in fact made the arrangement through the law of matrimony. Thus, therefore, matrimony has three goods. The first is that it is a function of nature in the sense that it is ordered to the production and education of offspring; and this good is the good of offspring. The second good is that it is a remedy for desire, which is restricted to a definite person; and this good is called fidelity, which a man preserves toward his wife, by not going to another woman, and similarly the wife toward the husband. The third good is called the sacrament, inasmuch as it signifies the union of Christ and the Church, as it says in Ephesians (5:32): "This mystery [sacrament] is a profound one, and I am saying that it refers to Christ and the church." This therefore is what he says. It has been stated that, it is good for a man not to touch a woman. But because all men are not equipped for this good, each man on account of the temptation to fornication should have his own wife, that is, determined by himself, so as to avoid uncertain and promiscuous concubinage, which pertains to fornication: "Rejoice in the wife of your youth" (Prov. 5:18); "Why should you be infatuated, my son with a loose woman" (Prov. 5:20).”