3- Potential problems that could plague any marriage: sex

What happens to a wife when she feels that her husband is using her for his own gratification only:

 "In the woman this produces an aversion to intercourse, and disgust with sex which is just as difficult or even more difficult to control than the sexual urge. It can also cause neuroses and sometimes organic disorder (which come from the fact that the engorgement of the genital organs at the time of sexual arousal results in inflammation in the region of the so called little pelvis, if sexual arousal is not terminated by detumescene, which in the woman is closely connected with orgasm). Psychologically, such a situation causes not just indifference but outright hostility. A woman finds it very difficult to forgive a man if she derives no satisfaction from intercourse. It becomes difficult for her to endure this and as the years go by her resentment may grow out of all proportion to its cause. This may lead to the collapse of the marriage" (Love and Responsibility, p.273-274). 

“The man must reckon with the fact that the woman is in a sense another world unlike himself not only in the physiological but also in the psychological sense. Since he has to play the active role in the marital relationship, he must get to know that other world and indeed as far as possible project himself into it emotionally. This indeed is the positive function of tenderness. Without it the man will only attempt to subject the woman to the demands of his own body, and his own psyche, frequently harming her in the process. Of course the woman too must try to understand the man, and simultaneously to educate him to understand her. Each of those things is equally important. Neglect of education and the failure to understand may both be the result of egoism.” (Love and Responsibility, p. 275-276).