About a dozen sessions later, my friend came away with critical insights: “I know I’m not perfect. I was very focused on taking care of my son, and my husband wasn’t getting from me whatever he needed. Everybody should be allowed to make mistakes and learn from them. We learned how to talk to each other and really listen. I love him and respect him, I’m so happy we didn’t split apart. He’s a wonderful father, a stimulating partner, and while our marriage isn’t perfect — whose is? — we are supportive and nurturing of each other. Working through the affair made us stronger.”

As happened with my friend, most affairs result from dissatisfaction with the marital relationship, fueled by temptation and opportunity. One partner may spend endless hours and days on work, household chores, outside activities or even social media, to the neglect of their spouse’s emotional and sexual needs. Often betrayed partners were unaware of what was lacking in the relationship and did not suspect that trouble was brewing.

Or the problem may result from a partner’s personal issues, like an inability to deal with conflict, a fear of intimacy, deep-seated insecurity or changes in life circumstances that rob the marital relationship of the attention and affection that once sustained it.

But short of irreversible incompatibility or physical or emotional abuse, with professional counseling and a mutual willingness to preserve the marriage, therapists maintain that couples stand a good chance of overcoming the trauma of infidelity and avoiding what is often the more painful trauma of divorce.

Ms. Weiner-Davis points out that “except in the most severe cases such as ongoing physical abuse or addiction,” divorce often creates more problems than it solves, an observation that prompted her to write her first book, “Divorce Busting.”

Ms. Weiner-Davis readily admits that recovering from infidelity is hard work and the process cannot be rushed. Yet, as she wrote in her new book, “many clients have shared that had it not been for their partner’s affair, they’d never have looked at, discussed, and healed some of the underlying issues that were broken at the foundation of their relationship.”

Rather than destroying the marriage, the affair acted as a catalyst for positive changes, Ms. Weiner-Davis maintains. In her new book, she outlines tasks for both the betrayed spouse and the unfaithful one that can help them better understand and meet the emotional and physical needs of their partners.