I talk often about "signaling," i.e., acting to show observers one's desirable qualities.  "Screening" is matching actions by observers, who can go out of their way to encourage signaling.  For example, you might insult someone to see how they react to insults.  Similarly, it seems evolution designed orgasms to help human females screen mates:

First suggested by David P. Barash nearly three decades ago, the idea is that orgasm might be a way a woman’s body speaks to her brain, “telling herself” that she has been having sex with a suitable partner—that is, one who is not worried about being displaced by a competitor, who is self-confident and unhurried enough to be satisfying to her.  When Barash was a graduate student more than ten years earlier, he observed that when subordinate male grizzly bears copulate, their heads are constantly swiveling about on the lookout for a dominant male, who, should he encounter a couple in flagrante, will likely dislodge his lesser rival and take its place. Not surprisingly, subordinate males ejaculate very quickly, whereas dominants take their time. …

Research on a large captive group of Japanese macaque monkeys is also suggestive. … During 238 hours of observations in which 240 copulations were observed, female orgasmic responses occurred in 80 (33 percent). Of these orgasms, the highest frequency took place when high-ranking males were copulating with low-ranking females, and the lowest between low-ranking males and high-ranking females.  … Maybe, [female orgasm] is designed to be more than a little hard to get, adaptive precisely because it can’t be too readily summoned, so that when it arrives, it means something. …

What about faking orgasm? … Orgasmic pretense might increase the man’s confidence regarding paternity of any offspring, building on his likely assumption that a sexually satisfied woman wouldn’t have sought to mate with someone else. … [This] would diminish the likelihood that the man will engage in “mate guarding,” thereby facilitating a woman’s ability to engage in extrapair copulations. …

Rates of extrapair paternity are about 2 percent in many human populations and about 10 percent in traditional societies. … One study has found that women are significantly more orgasmic when paired with men who are more symmetric. … [and] are more likely to experience ostensibly “high sperm retention orgasms” – that is, climaxes that occurred in close temporal proximity to the man’s.

We are often uncomfortable with acknowledging signaling theories of our behavior; signaling is often not our conscious motivation and we expect others would think less of us if signaling were our conscious motivation.  We are similarly uncomfortable with screening theories of our behavior, and for similar reasons. Yet the truth is that we are built to signal and screen much more than we realize. 

While the chapter above discusses women faking more desire than they feel, we should also expect them to sometimes fake less desire than they feel.  After all, if the strongest desires come when low status women mate with high status men, then strong desires tend to mark one as low status.  And while one typically wants to overstate desire for a relation before lockin, one typically wants to understate desire after lockin; those who want to threaten to leave if they are not treated better can prefer to understate their desire to appear more willing to leave.

HT to Tyler.