Several conclusions I've come to- boys and girls are built fundamentally differently: Boys fall in love with the person they consistently have sex with (else they would not continue), while girls have consistent sex with the one they fall in love with (else they would not continue). This is because boys are predisposed to trying to find someone to put their "seed" in, while girls are looking for security and comfort (see the book "Time, Sex and Power.") This comes into effect when a "rite of passage" has taken place--moving in, getting married, having kids (and thus having no physiological reason to have more sex)--so that because the couple is now "Official" (meaning they are "together forever") there is thus no reason to partake in such a "pointless" routine such as sex. Girls realize that they have found security and thus their libido, perhaps that tool used to find the man who will join them in "holy union", has achieved its objective and all is well for them. Boys on the other hand find themselves "trapped" in a situation they did not anticipate and feel they must bear their plight for the good of the marriage.
Perhaps this is because girls are future-oriented (the cliche that every girl dreams of her wedding day) while boys live in the moment (their own orgasm). The experience of life is diverse--after educating and sustaining one's self, the goal becomes to entertain one's self until he or she is dead-- and sex, the stimulation of sexual organs, often becomes taken for granted after a while. Girls believe they can have it whenever they want (since boys are always willing), while boys are motivated to have it as much as possible (perhaps even at the expense of their partner). The routine thus becomes monotonous so that the effect, unless the individual in question is driven towards the purely selfish objective of personal climax (undoubtedly a beautiful thing!), is that girls no longer want sex while boys find themselves in an untenable situation.
The question then becomes, where to get sex? Obviously the wife is unwilling, but should the husband settle for her decision? As individuals, we are obligated to maximize our own enjoyment of experience, so that even monogamy may become an outdated mode of existence, and therefore at least 3 options arise:
1) Break up and look to initiate another sexual relationship with someone else until that too fizzles out
2) Stay together and be unhappy in one particular aspect of the relationship
3) Engage in extramarital affairs, with or without the consent of your partner.
Options 1) and 2) seem inadequate in sustaining one's happiness, while option 3) necessitates a total and complete re-evaluation of moral aptitude. Again, is monogamy natural? While some animals (penguins) mate for life, others simply do not. Human beings are blessed with the insight and ability to reconstruct their environment to make it more pleasurable for their own experience so that by engaging in an alternative intimate relationship, one may rediscover a passion absent in a present one.
While honesty is certainly foundational to any relationship, keep in mind that decisions bearing significant relevance to the present relationship (deciding to move in, getting married...) were all based on the preconception that this moment (the orgasm) would continue far into the future. As this premise has certainly been negated, so too the basis for the relationship in question has also so that all participants might be given another opportunity to reassess all motivating factors, e.g. the ability to orgasm through a human connection sans masturbation.
Personally, I pledged early on in my life that I would make it a point to have sex every single day of my life, simply because that activity exemplified the pinnacle of experience and existence for me, so that if I was denied access by any other, that essentially represented a "breach of contract" if you will, thus releasing me from all obligations to stay "faithful" to an asexual partner.
Love may be present, but a broken heart may manifest if one is cheated on. What to do if the love of sex is hindered by an unmatched libido, characterizing the predicament concerning notions of happiness. Who gets what they want? Who wins? Who loses? Should one risk ending a relationship by partaking in any sexual experience with another they are drawn to? Maybe, though whether or not this decision is communicated is a decision left entirely up to the individual. We are all left up to our own personal moral guides to decide how to act and react to each passing moment, which is the only freedom we are each guaranteed in life. To think there is any authority on what to do or how to act is the only fiction there is.
Superficially entering into brief sexual encounters alone, without the possibility of coming to intimately know the other, may satisfy a basic desire but falls short of establishing a lasting connection out of which one might mature or come to know better his or her self. Yet eliminating any animalistic urge and rendering the self sexless for the "greater good" of this bond surely is no better. We are thus left with the undeniably atrocious complication of how to "have our cake and eat it to." Trying to reconcile the two modes of being creates a state of Antinomy, where moral standards may be called into question (Tiger Woods anyone?), yet there can be no assuredly "right" answer as to how to proceed. People fall in love with those they are near and close to due to the empathetic nature of the human experience. There should be no shame in choosing someone else to be near to, as no one can be considered qualitatively "better" than any other, aside from subjective preference. There can be no rational dialogue as we are guided purely by emotional expression (what feels good), and so we are victims of passion.
It seems girls enjoy the act of sex (the female orgasm), yet do not enjoy the external process of having sex--submitting to someone else's desire. Perhaps this is because of insecurity, fear of rape, lack of comfort, whatever. Either way, it constitutes a problem that can be addressed or ignored. Boys are often reared on notions of chivalry, a good thing, yet for the ends of harmonious reciprocity. Don't stay in a situation you hate.