In today's high-tech, mobile culture, "close relationships face enormous pressures," says sex therapist and writer Lonnie Barbach.

"As people spend more time with computers and live far away from their extended families, they require more nurturing from their intimate partners. A satisfying and loving sexual relationship is one way to meet this need."

Yet every year it seems a new Super Sex Secret hits the headlines, she says, "prompting people who've been perfectly happy with their sex life to start wondering if they're abnormal. I tell them, relax. There is no magic button.

"The more work I do on sexual problems the more I've come to respect individual differences. Our anatomy may be the same, but our preferences and pleasures are totally unique . . . The only thing that matters for a couple is what works for them."

Over the past 10 years, Barbach has helped hundreds of singles and couples discover "what works for them" through her private practice and work at the University of California, San Francisco. Best known as the originator of group therapy for women who have never experienced orgasm and the author of the now-classic guidebook for preorgasmic women, For Yourself, Barbach has broadened her focus from "me" to "we" with her latest guide For Each Other: Sharing Sexual Intimacy (Anchor Press/Doubleday, 305 pps., $13.95).

Stress on couples is intensified, she says, because "we live in a culture that demands total satisfaction. Years ago people got married, had children and lived their lives expecting troubles as a part of life. Now we expect everything to be perfect -- including our partner. We're less willing to compromise. If we fight, or have difficulty in a sexual area, we're less tolerant and figure that maybe what we need is a new partner."

But a change of partners, says Barbach, 36, is not necessarily the solution. "Almost everyone will experience some kind of sexual problem at some time in their lives. Probably between 30 to 50 percent of the adult population is currently having some form of sexual problem.

"A New England Journal of Medicine study showed that 63 percent of the women who defined themselves as happily married had problems with arousal or orgasm--and whenever one partner has sexual problems, or isn't satisfied, then both people have a problem. Single people with a number of different partners may experience even more difficulties."

Since intimate details are difficult to discuss "even with our sexual partners, many of us have worried silently for years that we are neurotic or sexually abnormal." Sexual concerns often reach disturbing proportions before prompting a visit to a sex therapist.

The two major problems that bring people to therapists, notes Barbach, are lack of orgasm and lack of desire -- both of which may be related to stress. "People under stress often don't feel very loving. Also, people today are worried about money and losing their job, and that affects their sex life. Men out of work often feel emasculated. Everyone's so busy, too, that they may just be too exhausted."

Sexual problems have three major roots, she says, "role scripting, relationship dynamics and the physiological and emotional components of sexual response." The goal of For Each Other "is to replace me . . . to help people be their own sex therapist and figure out the cause of their sexual problems."

Role scripting is Barbach's term for culturally defined behaviors individuals learn in order to fill certain functions--such as "ladies don't use certain words" or "men must initiate sex." Among common "role scripts" that affect sexual function:

* "Sex Is Good/Sex Is Bad" -- The contradictory message that sex is dirty, yet must be saved for a loved one.

* The "Fantasy Model of Sex" -- The sex act must be exactly as it's portrayed in B-novels. "That's like learning to be a doctor by watching 'General Hospital.' "

* The "We Can't Talk" Script -- It's too embarrassing to tell a partner what we like, and if it were true love, he or she would know exactly what we want anyway.

"With all these culturally based conflicts," says Barbach, "it's easy to understand why sex often does not just happen naturally. What is natural is the sex drive. Sexual behavior must be learned. It just takes sufficient motivation and practice to undo the negative training and learn new attitudes and approaches."

Physiological and emotional blocks to sexual satisfaction generally can be treated through exercises and therapy. Says Barbach: "That's what we're best at." Often therapy requires helping people learn about reproductive physiology and the sexual arousal process. Women may be introduced to "hidden" body parts linked to increased sensitivity, such as the pubococcygeal muscle and Grafenberg spot.

"Everyone is asking me about the G-spot," Barbach sighs. "It's an area of vaginal sensitivity for some women. Other women have different areas of vaginal sensitivity. Some women find stimulation of the G-spot pleasurable, others don't."

For Barbach, the "most challenging" sexual problems stem from relationship conflicts. "Playing detective is the most exciting part of my work." Her sleuthing is done through questions and answers -- "I've never had anyone I counseled take their clothes off, except one woman who showed the other members of a woman's group her masectomy scar."

A couple's sex life, she says, "very often can act as a barometer. Frequently a sexual relationship is a microcosm of the whole relationship. By examining our sexual relationship carefully, we also may gain a better understanding of how we and our partners interact on other levels."

The greatest single issue for couples to work out, she says, "is power. Who is going to control whom, who is going to decide what, who will get whose way? When two people are in a struggle to ensure that their needs are met by their partner, they can use two forms of power. One is a forceful power in which needs, wants and desires are asked for or demanded. The second is withholding power, which consists of not expressing feelings or holding back love or nurturing.

"When it comes to intimate relationships, neither form works well. Both engender resentment and further power struggles. Aiming for self-satisfaction and compromise rather than winning or changing one's partner is more effective in the long run."

Originally a math major, Barbach switched to psychology because she didn't want to teach math and was "always interested in social values and cultural rules." She began specializing in sex therapy "by serendipity. I was interested in doing my dissertation on women's consciousness-raising groups and was asked if I wanted to do sex therapy because I'd been doing some abortion and pregnancy counseling."

Currently Barbach is co-authoring a book with Washington social worker Linda Levine about men's sexual experiences. She is also enthusiastic about a book she plans to author with her writer/psychologist husband, dealing with relationship-rooted sexual problems. "Our theory is that every couple has the same fight over and over again. Different couples have different fights, and we want to look at the major ones.

"Also, relationships seem to go through stages. First people want to give to each other, then they become concerned with getting their own needs met, then -- if the relationship is to be healthy -- they transcend into a stage where they freely give to the other knowing their needs will be met, too."

Most sexual problems, she claims, can be solved in 12 sessions with a sex therapist. "When a couple does have a sexual problem," she says, "it's important to keep the level of intimacy high outside of sex while you go out and get information or therapy.

"When there's a problem, couples tend to avoid touching one another, thinking they don't want to be a tease. But that can create a distance between them that becomes a second problem to solve. Instead they can hold hands, cuddle and be affectionate. When sex is not going well, it's particularly important for a couple to demonstrate their love."