What Is an Extramarital Affair? Definition, Types & Causes

An extramarital affair is a romantic or sexual relationship that one or both partners conduct outside of a marriage or committed relationship, without the knowledge or consent of their spouse. The term covers a wide spectrum — from a single physical encounter to a years-long emotional bond that never becomes physical. Understanding what constitutes an affair, why they happen, and what forms they take is the first step to making sense of one of the most common and least discussed aspects of long-term relationships.

Extramarital Affair Definition

At its core, an extramarital affair is any relationship that violates the explicit or implicit boundaries of a marriage. Those boundaries differ between couples — what one couple considers an affair (intense texting with an ex) another might see as harmless. However, most definitions share three elements:

• Secrecy: The relationship is hidden from the spouse
• Intimacy: The connection is romantic, sexual, or deeply emotional in nature
• Breach of commitment: It violates the understood terms of the marriage

This is distinct from an open marriage or consensual non-monogamy, where both partners have explicitly agreed to allow outside relationships. An affair, by definition, involves deception.

What Are the 4 Types of Extramarital Affairs?

Affairs are not a single phenomenon — they take meaningfully different forms with different causes, timelines, and outcomes. The four most recognized types are:

1. Emotional Affairs

An emotional affair involves a deep personal bond, intimate sharing, and romantic feelings for someone outside the marriage — without any physical contact. These are often the most difficult for betrayed spouses to process, precisely because there is "nothing physical" to point to. Research consistently shows that emotional affairs can be as damaging to a marriage as physical ones, sometimes more so. Learn more about emotional vs physical affairs →

2. Physical Affairs

A physical affair involves sexual contact with someone outside the marriage, with varying degrees of emotional involvement. Some physical affairs are purely transactional with no emotional attachment; others develop emotional depth over time. The majority of affairs that end marriages involve a physical component.

3. Online Affairs

Online affairs occur entirely through digital communication — messaging, video calls, explicit exchanges — without the parties ever meeting in person. The rise of affair dating platforms and social media has made this category increasingly common. Many online affairs begin on dedicated affair dating sites and remain digital; others eventually transition to in-person meetings.

4. Long-Term Affairs

Some affairs last months or years alongside an intact marriage. These often develop a relationship structure of their own — regular meetings, shared routines, deep emotional attachment — while both parties maintain their primary partnerships. Long-term affairs are the most complex to understand and the most difficult to end.

How Common Are Extramarital Affairs?

Affairs are more common than most people acknowledge publicly. Research estimates vary widely due to underreporting, but the most cited figures suggest:

• Approximately 20–25% of married men and 10–15% of married women report having had an extramarital affair at some point
• Studies that use broader definitions of infidelity (including emotional affairs and online relationships) put the number significantly higher
• Infidelity is cited as a contributing factor in 20–40% of divorces
• The average extramarital affair lasts 6 to 24 months, though many are much shorter and some last for years

These numbers reflect only reported affairs. Given the secrecy involved, the true prevalence is almost certainly higher.

Why Do People Have Extramarital Affairs?

No single cause explains why people have affairs, but research identifies several consistent patterns:

Unmet emotional needs. The most common driver is not sexual dissatisfaction but emotional disconnection — feeling unseen, unappreciated, or lonely within a marriage. An affair fills that emotional void without requiring the difficult conversation of admitting something is wrong at home.

Sexual dissatisfaction. A significant decline in sexual frequency or compatibility is a known risk factor. This is particularly common in long-term marriages where intimacy has diminished over time.

Opportunity and novelty. The intensity of a new romantic connection — what researchers call "limerence" — is inherently exciting in a way that a long-established relationship cannot replicate. Some affairs begin simply because the opportunity presented itself and the pull of novelty was stronger than the commitment to fidelity.

Midlife transitions. Affairs peak in frequency during midlife, often coinciding with career changes, children leaving home, aging parents, or a general reassessment of one's life and choices.

Revenge or exit strategy. Some affairs are conscious or unconscious responses to a partner's behavior — a way to process anger, create distance, or initiate a separation without having to ask for one directly.

What Is the Difference Between an Affair and Cheating?

The terms are largely interchangeable, but "affair" tends to imply a more sustained relationship with emotional involvement, while "cheating" is often used for both one-night encounters and longer involvements. An affair typically implies some degree of ongoing connection; a one-night stand might be described as cheating but is rarely called an affair.

Is Flirting Considered an Affair?

Flirting alone — playful, lighthearted interaction — is generally not considered an affair by most definitions. However, sustained flirtation that involves emotional intimacy, explicit content, or a clear romantic intention crosses into emotional affair territory for most couples. The question is not always about the behaviour itself but about what the behaviour represents and whether it would need to be hidden from a spouse.

How Extramarital Affairs Start

The vast majority of affairs do not begin with a deliberate decision to cheat. They typically develop gradually through a predictable pattern: an innocent friendship or working relationship deepens; sharing becomes more personal; emotional intimacy grows; and a boundary is eventually crossed — often at a moment of vulnerability or opportunity.

Workplace relationships are among the most common starting points, precisely because they involve repeated contact, shared goals, and a natural context for personal conversation. Online platforms — including dedicated affair dating sites, social media, and messaging apps — have created an entirely new category of starting points that bypass the need for physical proximity entirely.

Extramarital Affairs and Divorce

Discovery of an affair does not automatically lead to divorce — in fact, research suggests that the majority of marriages where an affair is disclosed do not end in immediate divorce. Many couples attempt reconciliation, sometimes successfully. However, the long-term trajectory is significantly affected: marriages that survive disclosed infidelity often show lasting impacts on trust and relationship satisfaction.

In jurisdictions where divorce law still considers fault, documented infidelity can affect settlement outcomes — particularly in matters of property division and, in some states, alimony.

Key Concepts in Understanding Affairs

If you want to understand affairs more deeply, several concepts are worth knowing:

• The 80/20 Rule: The idea that people in affairs are often comparing the 20% of their spouse they are unhappy with against the best 80% of their affair partner — a distorted comparison that explains why affairs feel so compelling and why they so rarely survive contact with everyday reality
• Affair fog: The state of emotional confusion and intense attachment that often accompanies an active affair, impairing the judgment of the person involved
• Limerence: The state of intense romantic obsession characteristic of new relationships, which affair partners experience intensely because the relationship exists outside of mundane daily life
• Emotional infidelity: Intimacy and romantic connection that violates a relationship's boundaries without physical contact

Frequently Asked Questions

What is considered an extramarital affair?

Any romantic, sexual, or deeply emotional relationship conducted outside a marriage without the knowledge or consent of the spouse. This includes physical relationships, emotional affairs, and online relationships.

What is the most common age for affairs?

Research shows that infidelity rates peak in the 40s and 50s, often associated with midlife transitions. However, affairs occur across all adult age groups.

What is the average length of an extramarital affair?

Most sources estimate the average affair lasts between 6 months and 2 years, though many are much shorter (one-time encounters) and some last for years or even decades.

What is the difference between an affair and an open relationship?

An affair involves secrecy and a breach of commitment. An open relationship is one where both partners have explicitly consented to outside romantic or sexual connections. The defining difference is consent and transparency.

What is a secret affair?

All affairs are secret by definition — they are conducted without the knowledge of a spouse. The term "secret affair" is typically used to emphasize the lengths taken to conceal the relationship.