Infidelity isn’t a simple story of temptation, lust, or moral failure. It’s an outcome of complex, often hidden dynamics inside a relationship — and one common but under-discussed pattern is when the partner who’s perceived as less desirable (lower “mate value,” less social status, lower earning power, or less apparent attractiveness) is the one who strays. That might feel counterintuitive — if you’re the “less desired” partner, wouldn’t you fight harder to keep what you have? The research says not always. In many cases the less desired partner’s cheating can be driven by insecurity, perceived unfairness, opportunity, unmet needs, or strategic motives. Below are seven evidence-backed reasons this happens, each explained with practical examples and links to recent studies so you can see the data behind the claims.

1) Insecurity and fear of being replaced (attachment anxiety)

When someone feels less desirable, they often live with chronic anxiety about being abandoned. Paradoxically, anxious attachment can push people into two opposite behaviors: clinging or seeking outside validation. For some, an affair becomes a (misguided) safety net — a way to test the waters, regain a sense of desirability, or create an exit strategy in case the relationship collapses. Research connects attachment anxiety with a higher risk of infidelity, partly because anxious people are extremely sensitive to threats to the relationship and may act impulsively out of fear rather than secure commitment. ScienceDirect

Real-world example: a partner who constantly worries their significant other will find “someone better” might flirt online to see if anyone does find them desirable. That flirtation can escalate into an emotional or sexual affair.

2) Mate-value discrepancy creates jealousy, secrecy, and risk-taking

“Mate value” is a psychological term for how desirable someone is perceived to be as a romantic/sexual partner (looks, resources, status, personality). When partners see a gap — one feels markedly “better” on the mating market — the person who perceives themselves as lower value often experiences shame and vigilance. Studies show that mate-value mismatches are linked to higher jealousy but also to behaviors that paradoxically increase infidelity risk: increased surveillance, secretiveness, and sometimes acting out to reclaim status or attention. Recent large-scale research and reviews indicate that lower perceived mate value relative to the partner correlates with greater relationship strain and higher odds of cheating. MDPI+1

Real-world example: someone who believes their partner could “do better” may either overpolice the partner (which pushes the partner away) or start seeking validation elsewhere to feel “good enough.”

3) Resentment from perceived unfair trade-offs (inequity and compensatory cheating)

Relationships are negotiations: time, affection, childcare, money, social status. If the less desired partner feels they’re giving more (emotional labor, household work) while receiving less (admiration, status, sex), resentment builds. Cheating can become a form of retaliation or an attempt at rebalancing — consciously or unconsciously. Scholars who study motivations for infidelity find that “punishment” or “retribution” is a commonly reported motive; people sometimes cheat to hurt a partner who they feel has been unfair or uninvested. The University of Maryland’s research into infidelity motivations highlights that people cheat for a wide range of reasons beyond pure sexual desire, including to punish, escape, or replace a dissatisfying relationship. College of Behavioral Sciences

Real-world example: the partner who’s stayed home to raise kids while the other is promoted may feel invisible and, in a moment of anger or despair, seek an affair that feels like “getting even” and being seen.

4) Opportunity and perceived alternatives (dating apps, social networks)

Access matters. The “less desired” partner who suddenly has access to alternative partners — e.g., through dating apps, work travel, or social circles — may start to perceive better options exist. Research linking online dating and infidelity shows that the perception of high-quality alternatives reduces commitment and raises the likelihood of acting on temptation. Even the perception of viable alternatives can change behavior: it lowers the psychological cost of stepping outside the relationship. ScienceDirect

Real-world example: someone who felt stuck in a small-town relationship starts swiping while on a trip or after a friendship grows; the attention they receive online temporarily elevates their sense of desirability and makes cheating feel easier.

5) Low self-worth masked as bravado (compensatory status-seeking)

Sometimes the less desired partner overcompensates for feelings of inadequacy by pursuing conquests that boost status or ego. Cheating, in this context, is performative: it’s less about attachment to the new person and more about proving one’s worth. This is a well-documented psychological compensatory strategy — when self-esteem is low, people look for external trophies (affairs, flashy purchases, risky behaviors) to shore up identity. The behavior may start as a confidence boost and spiral into repeated infidelity. Studies on mating strategies and self-image support this pattern: when people feel low mate value, they sometimes pursue short-term mating tactics to demonstrate desirability. ScienceDirect

Real-world example: a partner who was consistently rejected in youth or who feels overlooked at work pursues affairs to feel “chosen” and admired again.

6) Power imbalances and the lure of control

You might expect the more powerful partner to be the one who cheats — and often they do. But power dynamics can cut both ways. Feeling powerless in a relationship can lead someone to regain control by stepping outside boundaries. Conversely, perceived low-status partners can also seek relationships where they feel more in control or valued. Recent experiments show that feelings of power (or lack of it) profoundly affect interest in alternatives and infidelity-related behavior. In other words, a partner who lacks control at home may look for control elsewhere, and that look can become an affair. Neuroscience News

Real-world example: a partner who feels overshadowed in social settings finds validation with someone who looks up to them, restoring a sense of agency they’re missing at home.

7) Strategic mate switching, boredom, or the search for a better match

Not all cheating is impulsive. For some, infidelity is strategic: a way to transition from one relationship to a better one without the painful limbo of being single. Evolutionary and social research suggests that when people perceive a possibility to “trade up,” they sometimes use affairs as a bridge — emotionally testing a potential replacement before breaking up. This can happen disproportionately when one partner sees themselves as less desirable and believes their current partner is likely to leave them anyway; starting an affair can feel like a way to secure a better future without risking complete loss. Multiple cross-cultural studies of infidelity motivations have documented mate-switching as a real driver for cheating behaviors. ScienceDirect+1

Real-world example: someone who’s long believed their partner is “out of their league” meets a new person who seems a better fit and initiates an affair to ease the transition.

What the research suggests overall (short synthesis)

Across recent studies, several clear threads emerge: (1) perceived mate value and power dynamics shape how secure people feel, (2) attachment style (especially anxiety) predicts risky behaviors aimed at reassurance or escape, and (3) opportunities and perceptions of alternatives (fuelled by dating apps and social networks) significantly increase the probability of acting on impulses. Importantly, infidelity motives are heterogeneous — researchers find everything from boredom, revenge, and emotional dissatisfaction to strategic mate-switching and ego-boosting. The picture that emerges supports the idea that the “less desired” partner’s cheating is often a symptom of insecurity, unmet needs, perceived unfairness, and increased perceived opportunities. MDPI+2ScienceDirect+2

Helpful next steps if this topic hits close to home

If you’re dealing with infidelity or fear of infidelity, here are immediate, research-backed steps that reduce harm and clarify choices:

1. Open but calm communication — talk about needs and perceptions of fairness; many grievances are repairable when aired respectfully.

2. Check attachment patterns — therapy can help couples recognize how anxiety or avoidance fuels unhealthy behaviors.

3. Limit opportunity — put boundaries around apps, travel routines, or contact that’s already causing stress.

4. Repair mate-value imbalance — this isn’t about changing appearance; it’s about redistributing admiration, appreciation, and visible investment so both partners feel valued.

5. Consider therapy — individual or couples therapy can unpack resentment, identify power imbalances, and work on lasting change.

Cheating by the “less desired” partner is rarely a mystery of sudden weakness; it’s usually the visible outcome of long-standing emotional imbalances — insecurity, perceived injustice, unmet needs, and new opportunities. Understanding the drivers behind these choices doesn’t excuse betrayal, but it does make responses more strategic and compassionate. When couples look beyond blame and into the underlying dynamics, they stand a much better chance of either repairing the relationship or parting in a way that preserves dignity for both people involved. If you want, I can turn this into a downloadable guide with scripts for those difficult conversations or a short therapy-style worksheet to map mate-value perceptions and unmet needs in your relationship.

Love Rubie xoxo