In addition to the set obligation of the mitzva of ona, which for most men is twice a week, it is a mitzva for every husband to have sexual relations with his wife when she desires him, as long as he has the strength for it, i.e., that he is capable of consummating the union.
Thus, the Torah’s commandment of ona has two parts. First, there are set times based on what the husband’s health and workload permit; these times provide a regular expression for the couple’s bond and mutual desire. It is precisely this regularity that gives expression to the stability of their loving relationship. It is also why the Torah refers to this mitzva as “ona,” “time,” when it mentions a man’s conjugal duties (Shemot 21:10).
Second, there is another part of the mitzva, which applies when the wife’s desire is aroused. The Torah commands the man to be responsive and to consummate their union with abundant joy. It is likewise a mitzva and a duty for the wife to be responsive to her husband, if he wishes to have sexual relations with her more often than required.
In light of the second component of the mitzva, a question arises regarding the first one: Why must the Torah establish set times for a couple to express their love for each other? Why not leave the frequency of the mitzva up to them? After all, according to the second component, if one spouse is in the mood, the other has a mitzva and an obligation to respond, even if this takes place daily. Conversely, if, over the course of several weeks, neither husband nor wife initiates intimacy, why must they be instructed to have sexual relations at set times?
There are three answers to this question. First, it often happens that as the years go by, life’s demands grow. Since sexual relations are no longer new and special as at first, the couple are liable to push it off, one time because of exhaustion, another time because of a preoccupation, the next time for a headache, and the time after that an upset stomach. Even though each time they both agree to forgo the mitzva, in fact their loving relationship is weakened. Deep in their hearts, each one is hurt that the other does not yearn for more intimacy, and when one does not initiate, the other also loses interest, deepening their sense of insult and the growing distance between them. Therefore, the mitzva of ona is there to instruct them to fulfill the onot on a regular basis. Only on rare occasions, when they are especially tense, may they forgo the mitzva by mutual consent.
Second, if the mitzva were always dependent on one spouse expressing desire, there would be concern that the spouse who is more often in the mood would become ashamed to always be the one to initiate. In contrast, when both husband and wife know that they have a mitzva to have sexual relations twice a week, they will fulfill the mitzva on a regular basis, and the need to indicate the desire for additional intimacy can be reserved for when one of them is feeling particularly amorous.
Third, as we mentioned above (section 4), the mitzva must be done with full attentiveness, with attention to tiny detail, much like an elaborate banquet. The Sages assessed how frequently a couple can fulfill the mitzva of ona in a wholesome manner, and this is consequently the mitzva of the Torah. If the man goes too far beyond this frequency, there is concern that it will become superficial for him, something he does just to satisfy his urges, without bringing proper pleasure to his wife. The unique joy of the mitzva would wane. To avoid that, and to ensure that the mitzva can be fulfilled properly, the Sages set a fixed frequency. Nevertheless, this is a general guideline; when a woman yearns for more, it is a mitzva for her husband to be responsive if he is able. Likewise, when a man yearns for more and feels that he can properly pleasure his wife, this, too, fulfills a mitzva.
Likewise, if a man wishes to have sexual relations with his wife more often than required, she must be responsive. Since nothing comparable to sustaining an erection is required of her, she may not refuse without a compelling reason (see the beginning of n. 12 below).
In both cases, even though the one who denies their spouse is violating a Torah commandment, he or she is not considered “rebellious” (“mored/et”), which would be grounds for divorce, since this is about sexual relations beyond the set times. In contrast, if one spouse avoids sexual relations at one of the times set in accordance with the husband’s health and workload, that spouse is considered rebellious and loses their ketuba rights (Responsa Rashba 1:693; Tashbetz 2:259; Ḥelkat Meḥokek 76:20; Maḥaneh Ḥayim 2:41, cited in Otzar Ha-poskim 77:1. See also MT, Laws of Marriage 15:18; Ba’er Heitev, EH 77:7; Meshiv Davar 4:35; and Igrot Moshe 4:75). Obviously, even at the set times of ona, a husband may not rape his wife if she refuses him. Rather, the only option available to him is to initiate divorce and cause her to lose her ketuba.
. People naturally differ. Some men naturally need sexual relations more frequently than the onot established by the Sages for the general population, based on their physical stamina and workload. Even when his wife cannot reach orgasm more than twice a week, because to do so she would need to get more sleep and be more relaxed, the couple should make sure that twice a week they fulfill the mitzva of ona completely. At other times when the husband is in the mood, they can fulfill the mitzva of ona pleasurably but without trying for the wife to have an orgasm. See below, 3:3 and 3:5, where we discuss Raavad’s fourth reason for being intimate at set times – to prevent people from sinful thoughts. Although this is less positive than the other reasons, there is still a mitzva to have relations for this reason. (See ch. 3 n. 4, where we explain when one should minimize the manifestation of one’s urges, and when it is forbidden to minimize them.)
As explained in the previous note, a wife may refuse to be intimate only when she has a compelling reason to do so. Pregnancy, nursing, or minor aches are not considered a compelling reason (below, n. 12).