Why People Cheat…and How to Heal When Your Partner Does

The Short Version: As painful as it is, cheating is part of relationships. Understanding why people cheat can help you understand past relationships scarred by infidelity and learn how to look for partners who won’t cheat. Dr. Stan Tatkin, the founder of PACT Institute, explained the series of communication violations that come with cheating and explored the situations and feelings that come with infidelity. He delved into attachment systems, unclear boundaries, and dysfunctional flows of information to expose the nuances of how and why cheating happens.

Betrayal is one of the most damaging things that can happen to a relationship. Betrayal of any kind compromises the sense of trust between two people, which is the foundation of a healthy relationship. When betrayal comes in the form of cheating, the fall-out is devastating and often relationship-ending. 

Like any other thing humans do in relationships, it’s important to understand why people cheat. By understanding the factors that influence infidelity, the root of why cheating hurts so much can be exposed and addressed. Dr. Stan Tatkin, the founder of PACT Institute, helped us understand why people cheat and how people who have experienced betrayal can heal.

The PACT Institute trains therapists in the PACT treatment modality, also known as the Psychobiological Approach to Couple Therapy. Dr. Tatkin developed PACT by fusing elements of attachment theory, developmental neuroscience, and arousal regulation. PACT has a reputation for helping couples who have not found success with other forms of therapy. 

Dr. Tatkin has seen countless couples throughout his decades-long career, and he shared some of his professional, experiential, and research-driven wisdom about infidelity with us. “At the core of cheating is a problem of withholding information,” Dr. Tatkin said. “It’s one person leaving the other out of vital information that they had the right to know. That’s the major violation.”

Dr. Tatkin said unclear, poor, or frequently violated boundaries in a relationship are risk factors for infidelity. Boundaries are the limits and standards we set for ourselves within relationships, and healthy relationships often rely on clear and well-communicated boundaries. If partners don’t set boundaries with each other, there are no guidelines for how each person should treat the other.

When boundaries have been set, if either partner can’t or hasn’t yet seen the consequences of breaking boundaries, they are more likely to continue to break boundaries. A crucial element of having and keeping boundaries in a relationship is a natural consequence of violating a boundary. Boundaries rely on consistent communication and are vulnerable to dysfunction when communication begins to break down.

Dr. Tatkin said some people who cheat feel a pull to people and experiences outside their relationship because of a lack of healthy communication and boundaries. “People go seeking,” he said. “They seek outsiders and outside excitement as a way to free themselves from this feeling of being trapped and confined and not being able to set boundaries and be themselves.”

“There’s another group that may cheat because they don’t feel they’re being attended to and cared for by their partner,” Dr. Tatkin said. “They’re not feeling loved and they feel like their partner isn’t interested in them, and so they will go elsewhere to fill that hole that’s being left by the distancing partner.”

People who cheat because they feel neglected by their partner may also cheat to get revenge on their partner. “They’re the most likely group to do it for revenge,” Dr. Tatkin told us. “Even though they’re cheating, they’re doing it to get back at the partner who isn’t showing interest in them.”

Cheating dynamics are complex, and Dr. Tatkin said even couples in open relationships can experience infidelity. “There are people who make arrangements to have open marriages, and people can still feel like they’re being cheated on despite the agreement,” he said. “This happens when agreements aren’t made honestly, and information is withheld.”

“The bigger problem with cheating is that one person left out a lot of information that the other had the right to know,” Dr. Tatkin said. “It leaves this open thought in the head of the person who’s been cheated on that their partner can lie to their face, can mislead them on purpose, and it’s so hard to resolve. It messes with the brain.”

The PACT treatment modality attends to the many aspects of what makes a person show up in relationships the way they do, and one of these aspects is how people form attachments to one another. Dr. Tatkin said that while attachment styles aren’t destiny-sealers, they can be used to understand the emotions and behaviors that lead to cheating. 

When it comes to distant and avoidant partners, Dr. Tatkin said these couples struggle with setting limits and feeling restricted by their relationship. “Distancing people are bonded with their partners, but they can’t set limits in the relationship to protect themselves,” Dr. Tatkin said. “They can’t feel like they’re free, and often it’s because they grew up in families who put an emphasis on the self, rather than the relationships.”

Dr. Tatkin said distancing partners are operating on their past experiences and behaviors they learned in childhood, and rarely distance themselves purposely. “They’re not doing it on purpose. It’s just how they adapted. Perhaps they saw their parents were distant, or their parents cheated, or their parents were not fully disclosed. They don’t think what they’re doing is wrong, and they find ways to justify it in their heads.”

Couples who don’t have clearly defined expectations and limits for their relationship often encounter a hard boundary for the first time when infidelity is exposed. “If someone cheats, and then the partner says I’m out, that throws them into a panic,” Dr. Tatkin said. “Before, the distant partner thought there was nothing they could do to lose their partner, and now they know they can.”

The pain of losing a relationship is often the only thing that causes distant partners to address their shortcomings. “If anything is going to reform them, it’s that,” Dr. Tatkin told us. “That’s what changes them, because it teaches them they can’t continue with the same behavior. And this isn’t just the case for a distant partner. This is human nature. We push the limits and need to know if those limits are real.”

Betrayal by an intimate partner or spouse, especially in the form of cheating, is painful. It can also influence how people operate in their future relationships. “Our survival ability to log and register harm is really healthy,” Dr. Tatkin said. “To increase my sensitivity to the cues that I might be harmed again is the way it’s supposed to be.”

Dr. Tatkin continued, “A natural outcome of being harmed or feeling harmed is the piqued ability to sweep for harm in the environment around us. It’s a bias and a neurobiological fact. We learn and then become better equipped to protect ourselves from a dangerous environment that we have more information on now than we did before when we were naive or had never been cheated on.”

People who have been cheated on navigate relationships differently, and Dr. Tatkin said it’s essential to understand, appreciate, and at times mitigate this difference. “We get hurt, we make mistakes, and our eyes increasingly open. We expand our knowledge of the world and its complexity,” he said. “That’s supposed to happen, but we’re not supposed to be paranoid.”

Dr. Tatkin said people with a history of traumatic experiences have heightened sensitivities to environmental cues. “These betrayal traumas begin to accumulate, and then we have a brain that is extra peaked for danger. We may start to become overly cautious and overly paranoid, and our lives become more and more limited as we push people away.”

It can be easy to feel scorned after being cheated on, and betrayal can cause many people to be wary or even scared of dating again. It can be difficult to trust after such a major violation. Dr. Tatkin said the key to moving on after infidelity is being able to adapt.

“When things happen to us, instead of just dying and giving up, we build mechanisms to protect ourselves,” Dr. Tatkin told us. “Even if those mechanisms are just focused on repair. We’re hurt by people, so we can only be healed by people. Moving into new relationships, when you make agreements that keep you safe and secure, vet those agreements thoroughly and don’t operate on assumptions.”