OraLabora,
I think that 1 Corinthians 7:3-5 can shed some light on the issue at hand in your marriage with your wife:
3The husband should fulfill his marital duty to his wife, and likewise the wife to her husband. 4The wife’s body does not belong to her alone but also to her husband. In the same way, the husband’s body does not belong to him alone but also to his wife. ***5Do not deprive each other except by mutual consent and for a time, so that you may devote yourselves to prayer. Then come together again ***so that Satan will not tempt you because of your lack of self-control.
I understand that there are medical issues involved which makes it difficult for you to enjoy sex with your wife. However, sex is not entirely about physical gratification. It is also about intimacy with your spouse. When one or both of you deprive each other of a gift that God designed to bring spouses closer together and that Paul commanded us not to abstain from for extended periods of time, then I believe you must prayerfully reconsider your course of action. When we follow God’s plan for our lives, all kinds of wonderful, unexpected things can happen. Your wife, as an evagelical Protestant, should be open to the words of Paul here. The Catechism supports the notion that sex within marriage is a wonderful and intimacy-building gift:
2360 Sexuality is ordered to the conjugal love of man and woman. In marriage the physical intimacy of the spouses becomes a sign and pledge of spiritual communion. Marriage bonds between baptized persons are sanctified by the sacrament.
2361 "Sexuality, by means of which man and woman give themselves to one another through the acts which are proper and exclusive to spouses, is not something simply biological, but concerns the innermost being of the human person as such. It is realized in a truly human way only if it is an integral part of the love by which a man and woman commit themselves totally to one another until death."143
"Tobias got out of bed and said to Sarah, “Sister, get up, and let us pray and implore our Lord that he grant us mercy and safety.” So she got up, and they began to pray and implore that they might be kept safe. Tobias began by saying, “Blessed are you, O God of our fathers. . . . You made Adam, and for him you made his wife Eve as a helper and support. From the two of them the race of mankind has sprung. You said, ‘It is not good that the man should be alone; let us make a helper for him like himself.’ I now am taking this kinswoman of mine, not because of lust, but with sincerity. Grant that she and I may find mercy and that we may grow old together.” And they both said, “Amen, Amen.” Then they went to sleep for the night."144
2362 "The acts in marriage by which the intimate and chaste union of the spouses takes place are noble and honorable; the truly human performance of these acts fosters the self-giving they signify and enriches the spouses in joy and gratitude."145 Sexuality is a source of joy and pleasure:
"The Creator himself . . . established that in the [generative] function, spouses should experience pleasure and enjoyment of body and spirit. Therefore, the spouses do nothing evil in seeking this pleasure and enjoyment. They accept what the Creator has intended for them. At the same time, spouses should know how to keep themselves within the limits of just moderation."146
2363 The spouses’ union achieves the twofold end of marriage: the good of the spouses themselves and the transmission of life. These two meanings or values of marriage cannot be separated without altering the couple’s spiritual life and compromising the goods of marriage and the future of the family.
You may not now nor ever understand why masturbation is wrong and sinful. In that case, keep in mind 1 Corinthians 1:20-21,22:
“20 Where is the wise man? Where is the scholar? Where is the philosopher of this age? Has not God made foolish the wisdom of the world? 21 For since in the wisdom of God the world through its wisdom did not know him, God was pleased through the foolishness of what was preached to save those who believe…25 For the foolishness of God is wiser than man’s wisdom, and the weakness of God is stronger than man’s strength.”
Sometimes we have to accept some ideas on faith alone. You may also want to check out what the Archbishop of Kansas City says about pornography and masturbation (
diocese-kcsj.org/Bishop-Finn/pastoral-07.htm)