Sam and Mari had been married for two years when Mari learned Sam was having an affair with a co-worker. Sam was working incredibly long hours in his job as a first year law associate at a very large firm. In their rare moments of quiet at home, Mari noticed Sam seemed increasingly distracted and she felt he was acting oddly secretive.When Sam was in the shower one morning, Mari grabbed his cell phone and looked at his text messages. In less than 10 seconds, her life had changed and what she saw struck her like a hammer between the eyes: I am going to screw you like there’s no tomorrow. From Sam to Molly. From her husband to another attorney. A woman who had been in Mari’s apartment just two weeks before.MORE: Why Work is a Hot Spot for RomanceThe rest of the evidence was easy to find, and it was clear as day on Facebook and in his email as well that Sam was in deep with Molly. Not only was he sleeping with her, but he appeared to be in love with her.On top of this all, Mari was six months pregnant with their first child.This was the basic information I learned when Sam and Mari arrived for couple therapy with me. Mari wanted desperately to save their marriage, but was understandably shell-shocked. “I really don’t know what I want right now,” she told me when we first met. “All this stress is terrible for the baby, I do know that much.”Sam was equally distraught in his own way. He admitted in front of Mari to being in love with Molly. Molly understood him in a way that Mari never did, he said, and he felt he had no choice but to pursue his feelings for her.MORE: What Makes Us Cheat?In her defense, Mari expressed some of the very best words I have ever heard in a therapy. It went something like this:“You’re so full of shit it’s unbelievable. You let yourself fall in love with her because you’re bored with your miserable existence as a lawyer and she shines a giant spotlight on your sad little ego. Your bosses beat on you, and I demand things of you because I am your wife and we have a real life together. What you have with Molly is an escape. It’s pure fantasy… fiction….and you can’t think straight because the hormones connecting your dick and your head have taken over your brain. Wake up.”Almost everything Mari had to say was the truth, and I love it when my clients can articulate their thoughts and feelings so brilliantly! In many ways, her statement captured truths that define nearly all extra-marital affairs. If only it would wake Sam up, my work would be done. Alas, our therapy was just beginning.You’ve probably heard that affairs in marriage are not uncommon. Roughly 40 percent of divorced men and women report having had an affair during their marriage, and I consider these estimates much closer to the likely truth of the matter than asking married couples if they’ve ever had a little something-something going on the side. What we don’t have a good idea about yet is the factors that will predict whether a couple can successfully weather the storm of an affair and, perhaps, make their relationship better in time.QUIZ: Are You Sexually Satisfied?The mere idea of a couple trying to make things work after an affair might seem ludicrous to you, but many couples do want to make their marriage work. The real question is whether the affair is a sign on the road toward divorce, or a symptom of a troubled marriage that can be nursed back to health.In the case of Sam and Mari, I provided them with the most scientifically valid treatment for couples struggling with an affair. The treatment involves several important elements, but at its core includes a careful examination of the affair’s impact on each person and the relationship, as well as a careful study of the reason for the affair in the first place. All of this work follows from establishing basic ground rules about whether and how much the participating person will have any contact with the outside person.QUIZ: What Kind of Love Are You (or Were You) In? Once these tasks are achieved, a major component of the model is cultivating forgiveness toward the participating partner and his/her transgressions. In order for a couple to move forward, each person must take responsibility for his/her own actions with the burden of responsibility on the participating partner. Finding forgiveness ultimately releases the couple from the control the affair has on their day-to-day emotions and allows the couple to solidify improvements in their relationship.When it works, this treatment is great. For Sam and Mari, I couldn’t get them over the hump. The arrival of their boy shortly after the revelation only added stress to their lives. Sam was in love with Molly, and it was revealed that he had an intense need for her adoration. As his spouse, Mari couldn’t satiate his need to be put on a pedestal and as a consequence Sam had a tough time entering back into the reality of his life.Although this particular case didn’t end well for the couple, or for me as a counselor, I have a lot of hope. Affairs happen for many different reasons, but the bottom line is that couples can recover in time if both people truly want to stay together and are willing to work for it. Part of the problem with staying together is that it’s hard damn work, and it’s often easier to withdraw than to give the relationship a genuine shot for improvement.MORE: How to Fight With Your Partner—Without Ruining Your RelationshipI hope you don’t have to struggle with these issues. If you do, I hope this column generates some ideas about moving forward and the factors to consider as you do so. Good luck!