Had Scarlett O'Hara and Rhett Butler just been a little more in tune with their feelings, more willing to share their unhappiness with each other in less accusatory terms, perhaps things might have been different.

As it was, Scarlett found herself trapped in a passionless relationship with Rhett, pining for another man, hardly caring at all for Rhett. And Rhett, blinded by his overwhelming love for her, let this continue - until the day came when he'd had enough and he left.That made all the difference. Suddenly, Rhett started looking pretty good to Scarlett.

It was, Dr. Dean Delis will tell you, a classic case of "the passion paradox."

Delis, a San Diego psychologist, says lots of couples find themselves in this position: One partner is more in love than the other. And the more the less-loved partner tries to save the relationship, the faster the more-loved partner withdraws, feeling trapped and guilty.

Delis describes this phenomenon in his newly released book, "The Passion Paradox: Patterns of Love and Power in Intimate Relationships" (Bantam Books, $17.95.).

All relationships have some imbalance. In the best, there's a kind of see-sawing. Getting back in balance keeps the romance alive, Delis says. But some relationships suffer a long-term imbalance, and these are the ones that are headed for trouble.

Delis defines the less-loved partner as being in the "one-down" position; this person suffers the pain of rejection and feels powerless, vulnerable and insecure. The more loved, the "one-up," suffers guilt, anger and frustration, not only at feeling trapped, but also at being unable to return the love their partner so freely gives.

"It's painful for both sides," says Delis. "Usually, we focus on the ispurned lover,' but the one-up is really a victim, too, because he wants to feel love for this person but something prevents it."

There's a chemical explanation for all this, Delis says.

When you're in love - when you start to lose control of yourself to another person - your brain starts releasing amphetaminelike chemicals. They're the same kind of chemicals released when you're in danger. This is just your brain's way of telling you to be alert, that you're vulnerable.

A side effect of these chemicals is the blissful state you reach with new love, or at the time you're trying to attract your partner. Once you feel certain of his love, you no longer feel so vulnerable.

"What almost always happens is that one partner is more successful at attracting than the other," Delis says. "Initially, that partner loves it because they no longer feel in danger. They know the other person loves them more, so they don't have to worry about being rejected. But because they're safe . . . the brain no longer needs these chemicals and they lose the passion."

Meanwhile, the other partner senses this and starts to feel even more vulnerable. Out pump more chemicals from the brain, producing an even stronger feeling of being in love.

While many therapists recommend couples caught in this trap recapture the balance by doing romantic things together - the "champagne-and-bubble-bath solution" - Delis says it rarely works because the one-ups and the one-downs have different sets of problems.

Instead, Delis suggests both partners attempt to balance the relationship - the one-down by getting some healthy distance from it, the one-up by giving closeness a try but keeping open the option to retreat.

Most importantly, he suggests the partners learn to discuss their feelings using "no-fault" language - not blaming or hurling accusations, but merely explaining why they're feeling the way they are. For example:

An accusation: "You came home two hours late and you didn't even call. I think that proves my point that you care more about your job and being a big shot than you do about me."

An explanation: "I have to tell you, I'm feeling like getting on your case because you came home so late and didn't call. And I don't want to start doing that again, so I think we ought to talk."

Other advice to the one-down:

- Tell the one-up you intend to get involved in outside activities to give yourself back some sense of your old identity. By backing off, this frees the one-up to love freely without feeling pressured.

- Stop yourself when you fall into the "hypercourtship" mode. It doesn't work, it just scares them away.

Advice for the one-up:

- Don't blame yourself for falling out of love. Realize that by feeling guilty you make it much harder to ever regain love.

- Stop dwelling on the partner's negatives; see positives as well.