Are we training for sprints or marathons?
What if the ideal sexual behavior for those who want to maintain a long-term pair bond is not the same as for those who prefer to change partners frequently? Perhaps there should be two norms for the sexually active—depending upon whether they wish to sustain a pair bond, or engage in sex without forming one.
The passion that is so effortless during the "honeymoon phase" of unions fools us into thinking that happy unions are dependent upon continued hot sex. As a result, we currently regard other strategies as dysfunctional. Frequent sex with orgasm for both partners is The Norm. And sexual enhancement pharmaceuticals and mainstream advice prod lovers to conform to it, regardless of their relationship goals.
In my experience, couples can achieve contentment and preserve the sparkle in their relationships without conforming to The Norm. The more I learn about the evolutionary roots of sex, what actually bonds couples subconsciously, and what is hidden in the neurochemical cycle of orgasm, the more sense it makes to codify two norms.
Since orgasm (and producing orgasm in another) feels so great, it seems like a no-brainer that, as Mae West once declared, "too much of a good thing is even better." For pair-bonding mammals like us, this may simply not be the case. Not only may frequent orgasm be less than the panacea it feels like it is, it may actually speed habituation between mates and trigger longings for novelty.
Unfortunately the lovers' honeymoon high—nature's two-year-maximum neurochemical grace period—wears off. That's when observant mates may notice that sexual satiety actually fosters subsequent emotional distance and amps up frustration. Homosexual partners in long-term relationships report that the same habituation creeps into their unions as well. Restlessness typically shows up well after any orgasm, so it's hard to match cause with effect.
Most of us blame this shift on anything but sexual satiety. Usually, when habituation sets in, too much orgasm seems the least of our worries. Nevertheless, the source of the phenomenon is likely to be closely related to perception changes brought on by sexual satiety, i.e., exhausting sexual desire. After all, ninety-seven percent of mammal species engage in sex to satiety—and then lose interest. This is a genetic program. Evidently, tension between this older program and our newer pair-bonding inclination serves our genes, even if it strains our romances.
Today's "orgasm is the cure" advice simply may not work for many long-term relationships (more's the pity). Perhaps we humans need to accept that we aren't the typical, promiscuous mammals who mate in a frenzy and then part to recuperate (unless a novel mate happens by). We are pair bonders. For us, romantic love (pair bonding) can even be a stronger urge than the drive to have sex. A harmonious pair bond ranks as the top determinant of human happiness and well-being.
We have evolved to benefit both physically and psychologically from close, trusted companionship and daily affectionate touch. Interestingly, other pair-bonding mammals don't engage in a lot of fervent sex. Most of their time is spent hanging out, mutually grooming, snuggling, and so forth. Perhaps for us, too, long-term comfort lies in frequent close contact, lots of gentle intercourse and rare orgasm, rather than vigorous orgasmic sex with little affection in between.
It's useful to keep in mind that neither very frequent / intense orgasm nor affectionate contact are mere physical events. Both trigger neurochemical changes in our primitive limbic brains that alter our moods, drives and priorities—including our desire to remain bonded (or not).
Granted, orgasm always feels like the cure to any problem in the short-term. Yet sexual satiety paradoxically increases subsequent dissatisfaction and a search for more stimulation. It may also make us yearn for a fresh start so we can get high on temporary drug-like honeymoon neurochemistry. In contrast, daily 
affection is a cue for contented pair bonding. It soothes the nervous systems of both men and women, acting as a natural anti-anxiety, anti-depressant. It eases cravings, lessening the need for frequent orgasmic relief.
Now, I know you're saying, "Well, we can have both." Yes, but for how long? Remember, lovers who orgasm frequently are sending each other mixed subconscious cues: one for "I've had enough; you now look like that fifth slice of pizza," and one for "You are adorable; getting even closer feels good." No wonder mates often feel like they're falling in and out of love as the neurochemical cycle of orgasm produces highs and lows, attraction and aversion.
So how did we come to collapse our sexual advice into a Single Norm for all lovers, whether or not they want a long-term relationship? My theory is that we train our experts to conform to The Norm, so they view "sex" as synonymous with "orgasm." Their mission becomes: more and better orgasms. To carry it out, they counsel intense sexual stimulation and novelty (short-term libido fixes).
Their research focuses on what arouses lovers and what produces climax—not on what happens after climax. They realize that sex is good, but assume that orgasm somehow bonds lovers without actually investigating which behaviors best sustain harmonious, satisfying pair bonds.
A fundamental distinction between strategies for pair bonders and those not seeking pair bonds could save everyone a lot of confusion and discouragement. Sex partners could steer their behavior toward sprints or a marathon with confidence. Tips for more frequent and hotter sex would be for "sprinters." Tips for careful cultivation of sexual desire and promoting closer bonds would be for "marathoners." Two norms would also reduce antipathy between groups who perceive their particular version of The Single Sexual Norm as either divinely inspired, or unjustly under attack.