Carmen McGuinness is a board-certified behavior analyst, acceptance and commitment therapist, and the author of three popular academic books for families.

Susan is the successful owner and operator of four metropolitan home design studios. She's attractive, intelligent, and confident. She’s also involved in an affair with a married man. Susan has been asked by close friends and family who are aware of the affair what drove a successful, attractive, intelligent woman to start and continue a relationship with a married man for nearly three years?

When a married man courts a woman, he takes a huge risk—a risk that reveals he wants her very much. His time with her, whether texting, secret coffee dates, or time spent in her bed, reveals a commitment much deeper than the single men she has been with. The single men just made a date. They didn’t have to engage in clandestine plans and think of elaborate excuses. And most single men confess they are initially very careful not to appear too interested, lest they find themselves headed for a commitment they're not ready for.

By comparison, the married man’s job in obtaining and keeping the attention of the single woman is to reveal his desire.

If he doesn’t show her how he feels with his eyes, his voice, the brush of his hand against her back, her shoulder, how will she know he wants her? And why would she stay with him if he doesn’t continue to work that magic that won her? The intimacy they share, the illusion he creates, is tremendously mesmerizing. She may perceive it as his commitment, an investment in their relationship. It may feel precious—something to be guarded and protected, nurtured.

But common sense will kick in. The friends she's told will remind her, “He’s married.” Worried family members will ask, “Is he still with his wife?” When she starts to emerge from the dreamy state he has put her in, she'll go in one of two directions. For many women, it’s out the door. For others, the game goes on—informed by these widely held opinions.

1. When a man roams, he is probably not happy at home.

2. Divorce rates are about 50 percent. Marriages end, and men remarry.

3. Infidelity rates are somewhere around 50 percent for men. Maybe lifelong monogamy isn’t the best plan.

For some women like Susan who aren’t attached but may be willing to engage with men who are, these well-known facts are enough to keep the dream alive—the dream of winning "Mr. Right" away from his wife—even if it means taking an increasingly tenuous emotional risk.

If women like Susan are very fortunate they'll learn more about the behavioral statistics of men who cheat before they decide to deepen their emotional risk.

1. The vast majority of men report that their reason for cheating was primarily sex.

2. Only a small minority of men who stray end up falling in love with their affair partners.

3. Most men who cheat report that they do so with multiple partners across many years.

In comparison to married men who cheat, the majority of women who enter into affairs with married men report that they do so because they are in love or falling in love with him.

There may be a vast disconnect between what Susan is thinking and what this man she thinks is the man of her dreams is thinking. Most women who begin a relationship with a married man are simply looking for a partner in someone else’s backyard. It may be morally or ethically wrong; it just depends who you ask. But this article is not about judgement. It's simply about understanding our natural tendencies and their origins.

If a woman in Susan's position digs deep enough into the infidelity blogs and self-help guides and finds these facts, she may just save herself before he ends the relationship. And, according to infidelity studies, this will likely happen around year three or four. Maybe he just can’t bear to look into her lovestruck eyes anymore. Maybe his wife is starting to suspect something. Maybe he’s just bored and ready for an affair-partner upgrade. But year four seems to be a drop-dead date in the data.

Whether she discovers these facts or not, her heart is destined to be broken. Broken relationships lead to broken hearts. However, some data point to the possibility that a broken heart after ending it with a married person can be much more difficult to heal than a broken heart after a more traditional relationship. Why? Researchers point to several possibilities.

1. She may feel like a double-loser, as she or he did not win over someone who, as all signs indicated, was less desirable.

2. Cheaters who end relationships tend not to be the most sensitive partners.

3. They may feel that the reasons for ending it should be obvious to their affair partner, and that she or he should just take it like a "big girl."

“You knew what you were getting into,” is a not uncommon reason to stop calling, stop emailing, stop texting, and if it is a workplace relationship, stop being nice at work.

4. Her support system may be in the dark about it.

Whether through shame, a desire to protect the cheater, or both, it is often true that no one knows of the relationship. If friends know, it may be only a best friend, or those in a close circle. And so, victims of broken relationships with married partners are often isolated, with little emotional support to help them heal.

So, how do the Susans of the world avoid injury from such a relationship? As is true with most things in life, knowledge is power. If the reader is considering a relationship with a married man, she might re-read the above facts very carefully before she proceeds. Life is short. Time may be better spent on a man who is looking for something more than a loveless sexual liaison with multiple partners over several years. That single guy might be a safer risk. Even if he’s pretending to be cool at first.

Want more insight into your relationship? Find out the things you should always be selfish about in your partnerships and the questions that could keep your marriage from ending.