The voice on the message had that familiar frantic tone of shock combined with urgency.

"Dr. Hendlin, could you please return my call as soon as possible? I need to talk. I found out my partner is cheating!"

Among married couples, research suggests that 20% to 40% of heterosexual married men and 10% to 25% of heterosexual married women will have an affair during their lifetimes.

Few experiences are as potentially emotionally devastating as learning your partner is having an affair. It cuts to the core of your sense of self. Feelings of rejection and pain wash over you and any semblance of trust in your partner is suddenly destroyed. Your world as you've known it is turned upside-down.

Most everyone who has gone through this experience can recall with excruciating clarity the particulars around their discovery of the indiscretion. And these details may become an obsession that torments one for days, weeks or even months to follow. The images and feelings of anger and resentment are, for some, too powerful to overcome and may lead to separation and divorce.

Historically, the context in which psychologists have understood and treated affairs was from the limited vantage point that pre-existing relationship problems must have caused the affair. Therapists who treat affairs have come to understand that to focus exclusively on relationship problems as the cause of the affair is to vastly underestimate the nature of affairs.

More current thinking is that people often have affairs because they can — not just because their relationship is suffering. Studies indicate in up to two-thirds of cases, marital problems are the effect, rather than the cause, of affairs. The implication is that couples, even in counseling, can get stuck in assigning blame and brooding on the emotional betrayal.

Our point here is that — believe it or not — a partner can be quite satisfied with many aspects of his or her marriage but still not have the impulse control, self-discipline or moral integrity to walk away from an opportunity. As you read that last line, notice whether you can accept that it could be true. Opportunity is the strongest predictor of affairs, with the need to prove one's desirability coming in a close second.

It is important to understand that most affairs can be successfully treated, particularly if both people are motivated to continue the marriage. A commitment to discussing the circumstances that allowed the affair to happen is essential, as is the ability of the acting-out spouse to demonstrate sustained empathy and understanding of the injured spouse's emotional spectrum.

There are a number of factors that converge in one's reaction, recovery and capacity to forgive and regain trust and security. These include general mental health, context of the affair, family background and willingness of the spouse to make amends.

As we approach Valentine's Day, it is easy to get caught up in an idealized version of love — hearts, flowers, unwavering love and a "together forever" mentality that can be especially difficult to accept when your world as you knew it has been altered. We want those of you struggling to put your situation in perspective and to know that it is possible to recover from an affair and to learn to use it productively to deepen the marital relationship.

STEVEN AND DEBORAH HENDLIN are clinical psychologists in Newport Beach. Read more at http://www.Hendlin.net.