Why did I cheat on someone I love?

I did it, but I still cannot say what I wanted.

Therapy with Mark will help you make sense of what you were reaching for.

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At a glance

The hardest part is often not what you did, but that you cannot explain it to yourself. Loving your partner and betraying them are both true of you, and holding the two together is where understanding starts. This article looks at what an affair tends to be reaching for, and what to do with an answer that excuses nothing.

Clinical insights from 22 years in psychotherapy

I’m Mark Colclough, MA, psychotherapist in Copenhagen. Qualified at the Psychosynthesis Education Trust and the University of East London. 22 years of full-time, face-to-face clinical practice.

  • The missing reason. Most clients who come to me after an affair can describe what happened in detail and still cannot say what they wanted from it.
  • An old appetite, not a new person. What clients tend to find underneath it is something they had quietly stopped expecting of their own life, and the affair was where it became available again.
  • Confession as relief. Clients often want to tell their partner at the moment the guilt is heaviest, which is the moment the telling is most about themselves.

Clinical notes: My observations are anonymised and compounded from my session notes since 2004.

Why can I not give myself a reason?

Every explanation you reach for is either too small to account for what you risked, or too large to be true.

If you say it meant nothing, you become a person who put a whole life at risk for nothing, and that is unbearable to hold. If you say you had stopped loving your partner, it does not fit the fear you felt at the thought of losing them. So the question gets held at arm’s length, and the not knowing turns into its own punishment, which is more comfortable than it sounds. Punishment at least gives you something to do with the feeling.

In my experience the reason is almost never one thing. It is several small things that were never said out loud over a long period, meeting an opportunity, at a point where you had stopped keeping track of your own state.

Does it mean I never loved them?

Love and betrayal can sit in the same person at the same time, and accepting that about yourself is harder than deciding you are simply bad.

Deciding you are simply bad is quick, and it has the advantage of ending the enquiry. It also leaves you with nothing to work with, and it quietly removes your partner from the picture, because a verdict on yourself is still a conversation with yourself. The more uncomfortable position is that you wanted your relationship and acted against it, and that both of those were you.

A review of the research on infidelity sets out eight motives people commonly report, among them anger at a partner, feeling neglected or mistreated, low commitment, wanting autonomy, wanting more sex or more intimacy, and situational factors such as stress; a review of that kind gathers other people’s studies rather than testing anything itself, so read the list as a map of what people say rather than as a finding about you.1 What strikes me about it is how few of those motives are about the other person at all.

What was I actually reaching for?

Usually it is a state rather than a person: to be wanted, to be new, to be nobody’s responsibility for an evening.

  • Being noticed. Attention of a kind that had drained out of ordinary life, including the attention you had stopped paying to yourself.
  • Anger with no route. Resentment that had no acceptable form at home, and that took an action instead of a sentence.
  • A self you had shelved. The person you were before the roles arrived, briefly available again and startling to meet.
  • Something that is nobody’s business. Where a life together has become organised and accounted for, an affair can be the only part of it that belongs to you alone.

These are possibilities to test against your own experience, not an account of you. A reason is not permission, and understanding why you did it changes nothing about what it did to your partner. The reason to look is more practical than moral: what went unspoken does not become harmless by staying unspoken, and until you can name it, it remains available to happen again.

Why does the guilt keep changing shape?

Guilt is about what you did. Shame is about what you have decided you are. They move in opposite directions and most people experience them as one feeling.

Guilt keeps your partner in view and pushes towards repair. Shame turns the attention inward, and from the outside it often looks like coldness: you cannot bear your own presence, so you withdraw, or you become defensive, and your partner reads that as indifference at the worst possible moment. Numbness belongs here too. When a feeling is too large to process it is common for nothing to arrive at all, which people then take as evidence that they do not care.

The same confusion drives the urge to confess at three in the morning. Telling your partner may be the right thing and it may be the honest thing, but the hour when the guilt is heaviest is the hour when the telling is most for you. That is worth knowing before you speak, not afterwards.

What do I do now, and when is understanding not the work?

End the contact before you try to understand anything, because nothing you conclude while it is still running can be trusted.

  • End it properly. Not paused, not on friendly terms, not left quietly available.
  • Write down what you were short of. The months before it, in your own words, with no reference to your partner’s faults.
  • Keep the explanation apart from the excuse. You will need to hold a reason in mind without it turning into a defence, and that takes practice.
  • Decide what you are deciding. Whether you want this relationship and whether you can live with yourself are two questions, and answering them together usually answers neither.
  • Expect slow movement. You can understand something in a week and still feel nothing has shifted for months, and that gap is ordinary rather than a sign of failure.

There are situations where this is not the work in front of you. If the affair is still going on, insight is being used to delay a decision. If your partner has just found out and is in acute distress, the immediate question is their state and the shape of the next few weeks, not your motives. And if there is fear or control in your relationship, in either direction, then what is happening between you needs looking at before anything else does.

If you want to look at this without your partner in the room, my page on one-to-one therapy after an affair sets out how I work with one person on their own.

Questions people ask

Can I come to therapy without telling my partner I am going?

Yes, and a good many people start that way. What you do with what you understand is a separate decision, and it does not have to be made in the first session.

Will you tell me I have to confess?

No, that decision is yours, and it carries real consequences that are worth thinking through rather than acting out. My work is to help you see what happened and what it means, not to deliver a verdict.

Is individual therapy worth it if we may do couples therapy later?

Often it is the better order. Doing your own part first means you arrive with something to say beyond apology.

What happens in a first session?

You tell me what happened and, more usefully, what you have not managed to say out loud to anyone. I am as interested in the months before it as in the affair itself.

Can I do this work if the affair was years ago?

Yes, and people often come long afterwards. An action you have never been able to explain tends to stay active in how you treat yourself.

Sources

  1. Love and Infidelity: Causes and Consequences. International Journal of Environmental Research and Public Health, 2023, a narrative review.

How this article was written: I choose the subject and the angle. An AI assistant researches and drafts. I read the draft, correct and improve it and stand behind every clinical statement. The professional and clinical judgement is mine.

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I’m Mark Colclough, MA, a psychotherapist and EFT couples therapist specialising in expats and international couples. If something here is close to what you are living with, a first conversation is free and there is no obligation.

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Mark Colclough

MA-qualified psychotherapist and couples therapist in central Copenhagen, practising since 2004. Advanced training in emotion-focused couples therapy and attachment theory. Works in English and Danish.

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