Noticed that this post has gotten a lot of attention. It is found with many other authentic sources in my book on Marriage which is available from Amazon (See sidebar)
Igros Kodesh (#1): 1) While it is true that asceticism in dealing with the lusts of this world is an important thing [assuming that it is done for the sake of heaven to give pleasure to G-d and not just to be more developed in spirituality] but that is only if it is done after he has already fulfilled is Torah obligations. However if by being ascetic he nullifies the slightest of his Torah obligations then his deeds are credited to the Sitra Acher [evil] - G-d forbid and he doesn’t advance in true spirituality. So even though he views himself as becoming a more elevated being by his asceticism he in fact is burying himself in the grave of pride by considering himself a very spiritual person when in fact his spirituality is seriously defective. And this frequently manifests itself as degradation in that it leads him to committing an actual Torah prohibition and he is not able to restrain himself at all as we know from a actual case where this happened – G-d should preserve us!
Conjugal rights of the wife is a Torah commandment just as serious as eating matzo. And even ignoring it when she is pregnant [when the wife has not truly excused him wholeheartedly from his obligations] makes into a complete sinner. And sins like this which are between two people are not atoned for even by Yom Kippur. He is like a robber or mugger who steals from his wife what is owed to her. This is comparable to killing his wife since it is known that the prime hope of a woman in this world is that she have a husband who loves her. Therefore when she see that he doesn’t love her, it is almost life threatening (pikuach nefesh) because of the great upset and anguish he causes her by making her like a widow while her husband is still alive.
The conjugal obligations of workers is twice a week, for a talmid chachom it is once a week. The Achronim write that in modern times we do not have people who are called talmidei chachomim according to Chazal [that is because in modern times we are not properly careful about not nullifying ourselves from Torah study and there are other reasons], nevertheless the reason why a talmid chachom only has an obligation once a week is because the Torah weakens his physical strength. That reason would therefore apply also a talmid chachom in modern times. However a talmid chachom who knows that he has the strength retains the obligation of having intercourse twice a week. This is how it is explained in the Biur Halacha (O.C. 240). This was the practice of the Chasam Sofer as is known – see the Mishna Berura there. It is also the practise of most talmidei chachomim in modern times ]before they reach old age ] It is obvious that she married with the understanding that her husband would follow the accepted practise. And furthermore the husband is obligated by the kesuba to conduct himself according to normative practise [for those similar to himself]. It is obvious that if he wants to exempt himself by have intercourse only once a week and not twice that this is close to creating a situation of a genuine uncertainty regarding a Torah obligation. Aside from that there is a separate obligation for the husband when he is aware that she desires to have relations – even if she indicates this by very slight hints as is explained in Shulchan Aruch (O.C. 240:1 which is from Pesachim 72 and in a number of other places.
2) The details of sexual intercourse of the mitzva of conjugal obligations are explained in the Siddur of Rav Yaakov Emden in the section of the laws of Shabbos night. It should be studied carefully because these are actual halachic obligations. Because according to the Torah it is prohibited to have intercourse in circumstances where the woman is not interested and therefore it is necessary to get her interested with intimate activities such as hugging and kissing until she is sexual aroused and desires intercourse. Because if this is not done first – it is like placing her before a lion who mauls and eats as is explained in Pesachim (49). [It is a terrible sin to deprive her of her sexual rights even if he is doing it for the sake of piety and asceticism. Taking what belongs to his wife can not be the basis of piety by theft and treating her as a slave]. Furthermore to have sexual intercourse against her will results in having children who are sinners and rejecters of Torah – they are call bnei anusa (children of rape).
A husband who grabs and has intercourse immediately without preliminary intimacy and then separates immediate after ejaculation and leaves her, might think that he is acting like a highly spiritual angel. But in actual truth he has not lowered his lust at all even though he definitely has placated his desires for the time being sine he has in fact obtained full pleasure from this intercourse. In contrast his wife felt no pleasures at all from this abrupt sexual act. In fact she has been hurt and shamed and the tears she sheds in private will not go unanswered. That is because our Sages(Bava Metzia) tell us that the Gate of Tears has not been closed. They say that a man should be very careful with his wife honor because she readily cries. There is no question that such a brutal act arouses Divine judgment against him. Furthermore he does not merit to have Divine help either in spiritual or material issues. And this that he mistakenly thinks he becomes a highly spiritual person by trying to be insensitive to his wife in sexual matters – this is a worthless fantasy and a lie. That is because from sins and transgression, one becomes blemished and spiritually impure – not elevated.
And this is stated in Shulchan Aruch (240:8) that it is done only after his wife is placated and is interested in doing it. Because otherwise it is prohibited to have intercourse without her consent as is explicit there in the Shulchan Aruch (240:3) and as is explained in the Siddur of Rav Yaakov Emden and this is actual Torah halacha. [In particular what is written in Shulchan Aruch (68). We see in Orchos Chaim in the name of Neziros Shimshon who writes that according to the Zohar and the writings of the Arizal – the halacha is in accord with the first explanation [that one should not have intent for the sake of pleasure but only for the sake of doing a mitzva]. However according to the second and third explanations [that they should be dressed during intercourse and that it should be done quickly] the opposite is true and there is a prohibition in doing this according to kabbalah. Nevertheless even according to the view of the Shulchan Aruch this is only if done with the full agreement of the wife. And thus is my understanding.
3) One who is intimate with his wife with hugging and other things for the sake of Heaven because he wants to have mercy on her that she shouldn’t be pained and feel abandoned – this will not cause the slightest weakening of his fear of Heaven or succumbing to lust. The opposite is true – it will bring him to holiness (kedusha) and he will be fulfilling the Torah command of imitating G-d. Just as He is merciful so to you should be merciful. Besides that hugging and kissing or any other act of intimacy is an inherent part of the mitzva of onah (conjugal duties) as is explained by the poskim regarding Shulchan Aruch (Y.D. 184:10) concerning the obligation when a man goes on a trip just before the time for his wife’s menstrual period.
4) While it is true that many talmidei chachomm conduct themselves in an ascetic manner in a number of intimate things – but that is only with the complete agreement of his wife and with her forgiveness with a full heart. And this agreement comes in most cases after it is explained to her that in truth her husband loves her and it is only for the sake of heaven that he is restraining himself. Or alternatively she married someone who is known as a tzadik whose reputation compensates for her loss of intimacy with him. But G-d forbid that the husband should conduct himself as an ascetic when it causes pain to his wife who is dependent upon him and does not forgive him whole heartedly concerning that which he is obligated to do for her.
5) Our Sages (Yevamos 62b) say, One who loves his wife as himself and honors her more than himself…is described by the verse "You should know that you will have peace with your wife…." It is important to note that our Sages are not saying to love one's wife with the natural love that man is attracted to a woman but rather to love her with the love that friends have for each other - as someone he knows and has a covenant with him and that they are partners in many things and each one helps and receives help from the other. In addition the love he feels for her should also come from gratitude. He needs to have the clear image in his mind that if he had not gotten a wife and would have remained alone and isolated - how much suffering and pain he would have from this. But now that he has a wife his life is in place and functioning. The significance of gratitude is immeasurably important. In fact our Sages state in the Mishna Rabbi Eliezer (Chapter 7) that all those who lack gratitude to their fellow men will eventually lack gratitude towards G-d. If you look there you will see how extremely stringent they are in this matter. This type of love is what our Sages say a man is obligated to have towards his wife. And again this love does not come from the lust a man has for a woman at all but from one of the good attributes which he is obligated to have. He needs to have this type of love and feeling towards her when he strives to cause her rejoicing at the time of intercourse and well as before and afterwards. Such a relationship is not disgusting – chas v'shalom – but rather it is a mitzva. In fact he should conduct himself in this manner even if he were not obligated by the Torah and surely now that the Torah does obligated it - as we mentioned before.