Some of Nemec's patients are young women who have just had a baby and trying to reignite desire after a pregnancy. But others are single women in their 20s who began having sex just to keep up with their peers.
"I call it the 'going along syndrome,'" she said. "By 17 they are sexually active and go along with sex, even if it doesn't feel good or they don't have a libido. If they go along at 18 or 20, they continue after they are married."
The danger is that if they don't deal with the issues of desire until they are older, "the husband finally gets Viagra at 60 and she's really in trouble."
That may have been the case with Joan (not her real name), a Texas woman who wrote to ABCNews.com.
"I have never had a libido, nor an orgasm," said the 52-year-old. "I have looked for ways with creams and pills but to no avail."
"I would love to find something to give me that feeling of wanting to have sex," she said.
Sometimes loss of desire is exacerbated by other physical problems. One of Nemec's patients, a 25-year-old newlywed, has a rare condition known as vulvar vestibulitis.
Jane, not her real name, has chronic vaginal pain -- a feeling of "burning and raw skin" -- and hasn't been intimate with her husband in months.
"I went off birth control pills, tried dilators and physical therapy and every cream in the world," she said. "I even tried Botox, but it didn't help."
"Every now and then I have the desire or urge, but then I just think about it being painful," said Jane, an occupational therapist.
She's lucky to have a supportive boyfriend, but it still takes its toll.
"In media everything is sex-based, and it's hard because you don't feel sexy," she said. "I have had this for so long, I am trying to build my self esteem in other ways."
For most women, low libido can be diagnosed with a five-question diagnostic tool, a questionnaire developed by the German-based pharmaceutical company Boehringer Ingelheim.
Some critics point to the pharmaceutical companies for creating new diagnoses like HSDD for the sake of drug sales.
Just last November, Boehringer Ingelheim's new drug flibanserin was hailed as the new female Viagra. A random, double-blind international study showed the drug appeared to increase sexual desire by enhancing mood.
The new drug works on neurotransmittors, not on blood flow, as does Viagra.
The PRESIDE study was also funded by Boehringer.
Study author Dr. Jan Shifren told ABCNews.com last year that women who have no sexual desire should not be "medicalized," but for those who were bothered by their lack of desire, "this group of women deserves effective treatment."
"If an effective and safe medication is identified, it should be available to women, but given potential risks and side effects, drug therapy always should be considered a last resort," said Shifren, who is director of the Menopause Program in the Massachusetts General Hospital Department of Obstetrics and Gynecology.
"Women in good relationships who are physically and psychologically healthy are generally satisfied with their sex lives -- and you'll never find this in a medicine cabinet," she said.
But Judith Steinhart, a health and sexuality consultant certified by the American Association of Sexuality Educators, Counselors and Therapists, said today's young women -- and men -- feel the pressure to be "sex pots."