Discovering your spouse has been cheating on you can be one of the most heartbreaking things in the world. And unfortunately, it happens too often.

Physical or emotional infidelity occurs in 41 percent of all marriages, according to the AP Journal of Marital and Family Therapy. And over half of both men and women admit to committing infidelity in at least one of any past relationships.

Psychotherapist Esther Perel has worked with many couples who contribute to these statistics. She spent 10 years traveling the world working extensively with hundreds of couples going through infidelity. Through her expansive experience, she's found three main reasons why people decide to cheat on their loved one, and they aren't what you'd initially expect.

1. "Looking for another self"

Perel tells a story of one of her patients - a woman who was blissfully married and had always done what was expected of her. She strived to be a good girl in all the rolls she filled - wife, mother, daughter. But she fell for a man quite the opposite of her with a truck and tattoos, and Perel determined the affair was a matter of the patient pining for a rebellious adolescence streak she never had.

"When we seek the gaze of another, it isn't always our partner that we are turning away from, but the person that we have ourselves become," Perel says. "And it isn't so much that we're looking for another person, as much as we are looking for another self."

2. Longing after a loss

Many of Perel's patients experienced a loss or hard-hitting news (loved one's death, scary health problems) shortly before having an affair.

When people experience death, questions about mortality and existence are raised. This existential crisis is often what drives people to make that cheating decision, says Perel.

"These questions are the ones that propel people to cross the line, and that some affairs are an attempt to beat back deadness, in an antidote to death."

So if a death or other similar traumas happen in your family, be aware that you or your spouse are more prone than usual to cross that fidelity line.

3. More about desire than sex

There's a widely held notion that affairs are all about sex or lust, but Perel's studies stand in stark contrast to that notion.

"Contrary to what you may think, affairs are way less about sex, and a lot more about desire."

Often when people decide to cheat on their spouse, it's because they want to be desired. They look for attention and ways to feel special or important. They're tempted by things they're not supposed to have, which creates a huge amount of desire.

What should you do when infidelity happens?

Of course, each couple's situation is different, and in some cases it's better to split while in others it's better to try for healing together.

For couples who want to work through the trauma, Perel says the number one thing that needs to happen first is the "important act of expressing guilt and remorse" for hurting your loved one. For the partner who cheated, it's important to feel remorse both for hurting your spouse but also for the experience of the affair itself.

For the deceived partner, it is "essential to do things that bring back a sense of self-worth, to surround oneself with love and with friends and activities that give back joy and meaning and identity."

Though affairs certainly come with hurt and betrayal, they also present an opportunity for growth, self discovery and new found capacity for forgiveness.

"Every affair will redefine a relationship," says Perel, "and every couple will determine what the legacy of the affair will be." Obviously, the choice is up to you and your partner, but sometimes coming back from infidelity can mean a stronger sense of self, and renewed vow of trust and a chance to start over in your marriage.