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g) Unreasonable refusal of marital intercourse is a grave matter. As has been explained, each spouse’s right to intercourse has limits, and usually when either is reluctant to have intercourse, the other should not insist. Still, sometimes a spouse has no justifying reason for being unwilling to cooperate. Such unwillingness can be motivated by anger and hatred, an unreasonable desire to avoid offspring, the manipulative use of marital intercourse to compel compliance in other matters, excessive preoccupation with other activities, and so on. Sometimes, too, one spouse without good reason travels alone or stays away from home for some time, thus depriving the other of the opportunity for marital intimacy. In all such cases, when the spouse deprived of marital intimacy makes it clear, by saying so or in any other way, that he or she desires it, the other should cooperate lovingly, and refusal is a grave matter.

The wrong of unreasonable reluctance to engage in marital intimacy admits of parvity but, like other injustices, only in cases in which, typically, the one who suffers the wrong considers it insignificant: for example, because intimacy is not denied for long and the unreasonable motive is not ill will but only some understandable weakness.

Of course, sometimes the spouses disagree about whether a refusal of marital intercourse is reasonable. Then both should try to find a harmonious solution, but if that is impossible, the spouse deprived of desired intimacy must remain faithful. Moreover, such a spouse should be tolerant, for even when a denial of intimacy is plainly unjustified, physical force, psychological coercion, nagging, and resentment are both incompatible with marital love and ineffective for obtaining the loving cooperation required for true marital communion.

h) Marital sexual acts short of intercourse can be chaste. Ejaculation by the male in the female’s vagina is necessary for sexual intercourse insofar as it is a reproductive function, and so such ejaculation is necessary for a complete act of marital intercourse. However, within marriage various sexual acts short of complete intercourse can be chaste. Of course, like intercourse itself, such acts are chaste only insofar as spouses seek in them, not pleasure alone, but the wider good of marital communion in which pleasure is a subordinate element. Therefore, what is said here about acts short of intercourse should be understood, not as advising the married how they can maximize sexual gratification without committing mortal sins, but as clarifying some of the requirements of marital chastity.

Marital sexual acts short of intercourse are good in themselves if they (i) are necessary or helpful to marital intercourse and/or (ii) express and foster marital affection. Still, even if good in itself, an act short of intercourse can be bad due to a wrong intention or some circumstance. Thus, such acts become bad if they either (iii) are intended to bring about complete sexual satisfaction apart from marital intercourse or (iv) are in some other way at odds with the good of marital communion.176

i) Mutually agreeable erotic words, looks, gestures, and bodily contact of various sorts, including manual and oral stimulation of the genitals, can prepare psychologically and/or physiologically for marital intercourse, and can intensify the experience of communion and make it more gratifying. Self-stimulating acts also can prepare oneself for intercourse.

ii) In the intervals between marital intercourse, interaction leading to moderate sexual arousal can both bring about a continuing experience of one-flesh communion and prepare indirectly and remotely for eventual marital intercourse. Thus, when abstinence from intercourse is appropriate, married couples sometimes rightly express and foster their affection by sexually stimulating interaction.

iii) Any act of the wife or the husband intended to bring about his ejaculation outside her vagina cannot be ordered directly to marital intercourse, and so is not a marital act. As will be explained, every attempt to obtain sexual satisfaction in a nonmarital act is wrong, and so such nonmarital acts always are morally excluded. If such acts are intended to serve in some way as means to the marital good—by maintaining intimacy when intercourse is impossible, satiating the sexual urge during a period of separation and so lessening temptation to commit adultery, treating sexual dysfunction, and so on—they are morally bad means to an ulterior good end.177

The wife’s complete sexual satisfaction (orgasm) is not necessary for sexual intercourse insofar as it is a reproductive function, but it does contribute to complete marital intercourse as a mutually satisfying experience of one-flesh communion. Hence, acts by the husband or the wife intended to intensify to orgasm her sexual arousal in continuity with any complete act of marital intercourse belong to that intercourse, and so they are marital, even if done during pre-intimacy or after the husband’s ejaculation and withdrawal. However, any act intended to bring about her orgasm through arousal in no way continuous with that involved in marital intercourse would be a nonmarital act, and therefore wrong.

iv) A couple’s sexual acts short of intercourse can be incompatible with marital communion in various other ways: by being repugnant to either spouse (with the result that they do not express affection), by using pornographic material to bring about sexual arousal (thus arousing adulterous desire toward a third party), by involving significant and avoidable risk of causing the husband to ejaculate unintentionally outside his wife’s vagina (thus interfering with complete intercourse and/or tempting him to intend the nonmarital satisfaction), by causing frustration and tension due to excessive arousal when intercourse is inappropriate, and so on.

Many acts that appear to meet the other criteria must be excluded inasmuch as they do not meet this one. For instance, some wives find oral stimulation of the penis repugnant, and for many men the practice leads to ejaculation outside the vagina. Again, any self-stimulation which does not pertain very closely to marital intercourse is likely to constitute masturbation or to be an occasion of that sin (see 2.f, below).

i) The circumstances of marital sexual acts should be suitable. Various circumstances can require abstinence. Couples should not neglect other serious responsibilities requiring a temporary separation or brief delay of marital intercourse. Serious health risks that can be avoided by temporary abstinence from intercourse require couples to practice such restraint, for example, for a few weeks before and after childbirth. Usually, to avoid scandal and/or serious distraction from the experience of marital communion, intercourse and acts short of it involving any exposure of or contact with the genitals must be conducted in strict privacy, and so must be delayed if privacy is unavailable.

In order that marital intercourse provide a full and mutually satisfying experience of communion and not be reduced to a routine function, couples also should try to arrange favorable circumstances. These often include lessening the frequency of intercourse, engaging in conversation and/or recreational activities as a context for sexual intimacy, and arranging a time free of excessive fatigue, distractions, and pressure to hurry. For the same reason, couples may either try to achieve simultaneous orgasms, if they think the experience will enhance their intercourse as communion, or dispense with that effort, if they find it more distracting than helpful. All such wholesome efforts to enhance marital intercourse as an experience of communion must be distinguished from the hedonistic use of techniques focusing solely on the intensification of erotic sensations.

Source: http://www.twotlj.org/G-2-9-E.html