In the early years of our marriage we read a number of books and listened to tapes on healthy marital love-making. These were from older deeply Christian men that Focus on the Family recommended: Ed Wheat and others who genuinely cared for couples and were able to counsel them into wholeness in the sexual area. They had a wide broad experience with sexual problems in marriages that they addressed lovingly and with wisdom—a far cry from online free-for-all counsel.
The upshot of their counsel was that marital sexual relations have to be mutually pleasing. If the wife tries something at her husband's suggestion and is uncomfortable with it for whatever reason, whether her past or her present sensation, she should not be forced. A husband who forces his wife is not exhibiting tender Christ-like self-sacrificial love for his wife like Christ loved the church. He must make his peace with his wife's avenues of response. “Dwell with your wife according to knowledge” (1 Peter 3:7). Every wife is different). Anything can happen at any time to a spouse that the other partner must accept and adapt to. A wife can become a vegetable due to an auto accident, become a quadriplegic like Joni Erickson who IS married (think of how patient her husband must be), or have his wife grow prematurely old on him where her skin (in the marital connection area) loses elasticity and chronically rips. Marriage requires the love of God, through thick and through thin. The goal of all marriage is not the pursuit of personal happiness but rather learning to die to self, so that we might take on Christ-likeness.
When a husband forces his wife to do anything sexually, she may accomplish it physically but if because her heart is compromised, she may totally shut down, rendering any experience impossible for that episode. Her body simply won't secrete the juices. So much of sex proceeds from the mind and heart. It is an extremely delicate dynamic for both men and women, but the woman is so delicate psychologically that it is only tender love that opens her up. A man who forces himself on his wife doesn't realize that he jeopardizes his entire future sexual life with her—and her adoration and comfort levels with him. (The definition of a rape is not having mutual consent; rapes are rapes because force was involved.) She has to be given a safe environment to grow to trust him in this area in order to open up more and more. He must keep the future 40 years in mind; he is building (shall we say, erecting) something in his marriage that he will reap—either in negative consequences or in delights.
Conversely, a woman needs to show readiness and eagerness and joy in the sexual times, putting aside her own delicacies/headaches/inconveniences to affirm her man via the sexual act—because it is primarily through this act that the man feels validated. Thus (within the parameters cited above) she must be sacrificial and Christ-like in giving her husband this joy. It takes a selfless love, from directions.
If you suspect a problem, get professional help, right away.