"Why did the affair happen?" -- An important question!

When couples come to me in the aftermath of infidelity, one of the first questions they often ask is whether their relationship can recover.

The answer is: it depends.

Two things matter enormously: why the affair happened, and whether both partners are willing to do the difficult work required to repair the relationship. Spoiler alert: It's going to be a huge challenge for the party who had the affair.

Many couples do choose to stay together after an affair. But staying together is not the same as truly healing. Rebuilding trust, restoring emotional safety, and reconnecting in a meaningful way usually take time, honesty, patience, and sustained effort. Working with a therapist trained in evidence-based couples approaches, such as the Gottman Method or Emotionally Focused Therapy (EFT), can help provide structure and support for that process.

Sometimes, perhaps surprisingly, couples who do this work end up feeling closer and more connected than they were before the affair. But there is no quick route to that outcome. And for some people, the healthiest decision is not reconciliation, but recognizing that they no longer want to do this work within the current relationship.

Why did the affair happen?

The betrayed partner almost always wants to understand why the affair occurred. Sometimes the partner who had the affair is asking the same question.

That answer matters.

Note: By “infidelity,” I mean emotional or sexual involvement outside the agreed-upon boundaries of a relationship, typically involving some degree of secrecy or deception. Consensual non-monogamy is a different situation and is not what I am referring to here.

There is no single explanation for infidelity. Affairs can arise from many different circumstances, but several patterns show up repeatedly.

Conflict avoidance

No two people enter a relationship with perfectly aligned needs, preferences, expectations, and desires. Differences are inevitable.

Healthy relationships require couples to notice those differences, talk about them, and negotiate around them. Those conversations are not always easy. They may involve sex, money, parenting, household responsibilities, emotional needs, family boundaries, or plans for the future. Differences in sexual desire are one particularly common example.

When partners repeatedly avoid these conversations, the relationship can gradually lose energy and intimacy. Daily life becomes more routine, unmet needs remain unspoken, and resentment may quietly accumulate.

Rather than taking the emotional risk of confronting those tensions directly, one partner may begin looking outside the relationship for connection, validation, affection, or intimacy.

Understanding this does not excuse the affair. Looking outside is always a choice. But it can help identify what was happening in the relationship before it occurred, and provide a roadmap to repair what was missing or not working.

Being locked in constant conflict

Some couples do not avoid conflict at all. Instead, they become trapped in it.

Both partners may become highly skilled at defending their positions, explaining why they are right, and pointing out where the other person is wrong. Over time, conversations begin to feel less like attempts to understand one another and more like arguments that must be won.

What gets lost is the kind of communication that creates emotional bonding: allowing yourself to be influenced by your partner, becoming curious about their perspective, acknowledging your own fallibility, and showing vulnerability. When these things disappear, both people may begin to feel lonely even while living together.

The relationship can start to feel adversarial rather than safe or warmly connected. A person who feels chronically misunderstood, criticized, or emotionally alone may become especially vulnerable to a connection with someone who seems accepting, attentive, and easy to talk to.

Again, this does not justify an affair. But the longing underneath it may be a longing for emotional connection and safety.

Novelty

New relationships have a particular kind of energy. They're fun.

People are often presenting the best versions of themselves while simultaneously viewing the other person through an optimistic, idealizing lens. There is discovery, anticipation, and possibility. That experience can feel intensely alive.

Long-term relationships are different. Eventually, we see the whole person—and they see us. We encounter habits, limitations, disappointments, stress, responsibilities, and the ordinary messiness of shared life, and the disillusionment of seeing another person more fully and imperfectly.

For some people, a new relationship becomes an escape from that complexity. The freshness of the connection can feel like falling in love all over again.

In some cases, a person repeatedly pursues the newly-in-love feeling itself. If someone struggles with chronic emptiness, insecurity, or a need for external validation, the intensity of a new romantic connection may temporarily make them feel unusually alive or complete.

The difficulty, of course, is that this stage never lasts forever.

When this pattern becomes repetitive or compulsive, recovery requires more than simply ending the affair. It may involve understanding the emotional needs driving the pattern and developing healthier ways to tolerate ordinary intimacy, disappointment, and vulnerability.

Falling in love with someone else

It is also possible for someone to genuinely fall in love with another person while still being deeply attached to the life they have built with their partner.

A person may love their home, family, shared history, future plans, social identity, or sense of stability—and at the same time develop powerful feelings for someone who exists outside that structure.

Sometimes this happens in relationships where the person who strayed was never deeply emotionally connected to their partner in the first place, but valued what the relationship provided: companionship, family life, security, belonging, or a shared future.

These situations can be especially painful because the conflict is not simply between two people. It may be between two different versions of a life. In some cases, the affair is not voluntarily disclosed and instead comes to light through the third person or through discovery by the betrayed partner.

The relationship is already over

Sometimes an affair functions, consciously or unconsciously, as an exit strategy.

A person may already want to leave the relationship but feel unable to say so directly. They may fear conflict, guilt, responsibility, or the pain they know they will cause.

Instead of ending the relationship themselves, they behave in a way that makes the other partner end it for them.

In therapy, this situation can become particularly difficult when the partner who wants to leave hopes the therapist will somehow absorb, manage, or soften the other person’s anger and grief.

But ending a relationship still requires emotional responsibility. A therapist can help people navigate an ending more safely and respectfully, but cannot take away the pain of it.

Understanding the “why” is only one part of healing

Understanding why an affair occurred can be enormously important. It can help both partners make sense of what happened, identify vulnerabilities in the relationship, and determine whether meaningful change is possible.

But understanding is not the same as excusing.

And understanding the cause of an affair is only one part of deciding what comes next.

For some couples, that next chapter is reconciliation, accountability, and the slow rebuilding of trust. For others, it is separation and the work of ending the relationship with as much clarity and dignity as possible.

Either way, the question of why matters because it helps answer a larger question:

What would actually need to change for this relationship—or either person within it—to move forward in a healthier way?

For more about the work required from each partner after infidelity, see the accompanying article, “What It Takes to Reconcile After an Affair.”