Infidelity has always been one of the most difficult challenges a relationship can face. It’s not just a “mistake” or a passing fling; it cuts to the heart of what marriage is built on: trust, loyalty, and emotional safety. When that trust is broken, the impact can be devastating. For some couples, it’s a wound that can never fully heal, leading to separation or divorce. For others, it becomes a turning point that forces them to reassess their relationship, where they seek the help of counselling or mediation.
Infidelity has always been one of the most difficult challenges a relationship can face. It’s not just a “mistake” or a passing fling; it cuts to the heart of what marriage is built on: trust, loyalty, and emotional safety. When that trust is broken, the impact can be devastating. For some couples, it’s a wound that can never fully heal, leading to separation or divorce. For others, it becomes a turning point that forces them to reassess their relationship, where they seek the help of counselling or mediation.
In the UK, affairs remain one of the most common reasons marriages end, even though the legal system no longer requires couples to cite adultery as a ground for divorce. Despite this, the emotional weight of infidelity hasn’t changed, and it still leaves partners struggling with anger, betrayal, guilt, and confusion about whether the relationship can, or should, survive.
How many people have affairs?
The question of how many people have affairs is one that sparks curiosity and discomfort in equal measure. In the UK, surveys suggest that around one in five British adults openly admit to having had an affair at some point in their lives. That’s roughly 20% of people; meaning if you gathered ten married couples in a room, the odds are that several of them would have faced infidelity in one form or another. And that’s just the number of people who are willing to own up to it. Affairs, by their very nature, thrive on secrecy, so the actual figure is likely to be much higher.
When you translate this into the context of marriages and long-term partnerships, it means that roughly one in five committed individuals has stepped outside their relationship at least once. In many cases, these aren’t just fleeting encounters either; many report ongoing affairs that last months or even years. Research also shows that infidelity isn’t confined to any particular age group or social class; it cuts across the board, from young professionals navigating online dating temptations to long-married couples struggling with unmet emotional needs.
Cultural factors also play a role in shaping how we see infidelity. In Britain, where the “stiff upper lip” stereotype often keeps private lives tightly under wraps, the willingness of 20% of adults to admit to cheating suggests that affairs may be even more woven into the fabric of relationships than many imagine. Add in the rise of workplace romances and the ease of connecting online, and it becomes clear why so many couples find themselves navigating the fallout of betrayal.
What percentage of marriages experience infidelity?
UK surveys from pre-COVID years found that 57% of men and 54% of women admitted to having cheated in one or more committed relationships. These figures are likely to include both married and unmarried relationships, but still illustrate the prevalence of infidelity. Taking a conservative estimate, it can be seen that roughly one-third to one-half of UK marriages experience infidelity at some point.
How many marriages end in divorce due to infidelity?
Prior to introducing no-fault divorce in April 2022, adultery was a legally recognised ground for divorce, and remains a powerful emotional reason behind breakdowns. One estimate suggests that around 1 in 7 divorces in the UK were granted because of adultery. Another source estimates that about 14% of marriages end in divorce because of adultery. It would appear that while relationships break down for a variety of reasons, infidelity remains a notable trigger for divorce.
What percentage of cheaters admit their infidelity?
Self-reported admissions remain the most accessible data points. In the UK:
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57% of men and 54% of women acknowledged having cheated in one or more committed relationships
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Nationally, 1 in 5 British adults admitted to having an affair (20%)
In other words, plenty of people who stray are willing to put their hand up and admit it, but the likelihood is that the real number is even higher, since many keep that secret firmly to themselves.
Why do people cheat?
Surveys and polls carried out in the UK indicate these as common reasons people cheat:
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Emotional connection: Many engage in affairs with friends (over 30%) or co-workers, suggesting proximity and emotional availability play a big role
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Online opportunities: Around 20% of affairs began with someone met via social media or dating apps. There are also those that have affairs with AI personalities.
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Unmet needs: Many psychoanalysts cite unresolved childhood trauma and unmet emotional needs, not just sexual desire, as leading causes behind affairs
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Opportunity and impulsivity: Personal stories highlight “just the opportunity” as a motivator without underlying relationship issues
Cheating often stems from complex emotional needs rather than one simple cause, and these statistics provide the evidence of the many causes.
How many people have affairs at work?
Infidelity in the workplace is a common scenario, and perhaps one of the most understandable. We spend so much of our lives at work, often more waking hours with colleagues than with our own partners, so it’s not surprising that close bonds can form. According to UK surveys, around a third of people who cheat say they met their affair partner at work, making it one of the leading settings for infidelity.
The office can create the perfect storm: long hours, shared projects, late-night deadlines, and the camaraderie that comes with navigating stress together. Add in after-work drinks or business trips, and professional boundaries can start to blur. For some, what begins as a harmless friendship or a bit of banter evolves into emotional intimacy, which then crosses into a physical relationship.
The workplace also provides a layer of cover that can make an affair easier to sustain. Regular contact can be explained away as work commitments, and secrecy thrives when time spent together looks perfectly legitimate from the outside.
What percentage of affairs last?
Data on the length of affairs is sparse, but global estimates suggest that once an affair begins, it lasts an average of two years. While this figure isn’t specific to the UK, it offers a useful reference point. If we assume similar patterns, a significant portion of affairs last way beyond fleeting encounters. Determining exactly what percentage turns into long-term relationships would require further study to be carried out. Still, anecdotal evidence and counselling experience reveal that some affairs do grow into sustained relationships, especially when emotional needs are consistently unmet in the primary relationship.
Infidelity and no-fault divorce
Since April 6, 2022, the law in England and Wales has operated under no-fault divorce. This means that couples no longer need to prove adultery, unreasonable behaviour, or separation for 2 or 5 years. Instead, they declare that the marriage has “irretrievably broken down”.
Adultery no longer affects legal outcomes such as financial settlements or child arrangements, unless linked to serious financial misconduct. The law now encourages more amicable endings without assigning blame.
Final thoughts
The question, how many people have affairs isn’t just about numbers. It reflects deeper questions about emotional needs, and relationship health. With up to half of people in committed relationships admitting to infidelity and a significant portion of these leading to divorce, it is clear that affairs remain a key factor in marital breakdowns.
At the same time, legal reform through no-fault divorce is shifting how infidelity matters in divorce proceedings, less as legal grounds, more as an emotional catalyst that leads to separation and divorce.
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