An exclusive extract from 'The Opposite of Happiness: How Bad Feelings Make and Break Us', by George Loewenstein.
24 September 2026
O, beware, my lord, of jealousy!
It is the green-eyed monster which doth mock
The meat it feeds on.
—William Shakespeare, Othello
The Green-Eyed Monster
While jealousy and envy are often confused, they have distinct meanings: Envy, as we've seen, frequently involves wanting what someone else has. Jealousy is a different beast – it involves feeling threatened or fearful of losing what you already possess, especially another person's love or affection.
The famous passage above from Othello – perhaps the greatest work of literature on the subject – captures not just jealousy's intensity and self-destructiveness, but the way it mocks the person in its grip. It can lead you to spy on someone who has nothing to hide, to act cold or hostile toward perceived rivals, or to torture yourself by imagining betrayals that are probably never going to happen. You sense, deep down, that your suspicions are absurd—yet somehow you can't put them to rest.
Although I've seen Othello multiple times – it is my favorite of Shakespeare's plays – I find each time agonizing. Othello is driven mad, and Desdemona is ultimately killed, by a false belief: that she's unfaithful. Even though I don't think 'straying' in marriage should be treated with the kind of moral absolutism it often receives, I still find Othello's jealousy more painful to watch precisely because it's unjustified. If Desdemona had truly been "cheating on him" (to use the unfortunate contemporary term), the tragedy would feel less tragic.
Why are we built this way, to torment ourselves over threats that don't exist? Why do we so often fear losing people who are not, in fact, going anywhere, or who might not have gone anywhere – if jealousy hadn't gotten the better of us? Jealousy does, after all, often become a self-fulfilling prophecy: we accuse, obsess, cling too tightly, and in doing so, we drive away the very person we so fear losing, sometimes into the arms of the person we are jealous toward.
The problem begins with the way jealousy distorts perception. A single hint – a delay in response, a changed tone, a short message where a long one is expected – is enough to trigger a feedback loop that turns suspicion into conviction. Psychologists call this tendency confirmation bias – the habit of interpreting the world in a way that supports what we already believe.
Confirmation bias results, in part, from the way we collect data. When tasked with assessing whether someone is an extrovert, you might ask, "What would you do to liven up a party?" – a question that assumes the very trait you're supposed to be testing. Another cause of confirmation bias has to do with the biased way we interpret ambiguous data. Jealous people do something similar. In one scene, Othello touches Desdemona's hand and finds it warm. That simple fact becomes, in his mind, evidence of something sinister:
Hot, hot, and moist. This hand of yours requires
A sequester from liberty, fasting and prayer,
Much castigation, exercise devout;
For here's a young and sweating devil here.
And Shakespeare, as if to generalize the madness, offers this:
Trifles light as air
Are to the jealous confirmations strong
As proofs of holy writ.
The Origins of Jealousy
Jealousy is not confined to romantic relationships. One can feel jealous when a close friend grows close to someone else, or when a sibling seems to be favored, or when the new guy at work starts getting the compliments you used to receive from the boss. We can jealously guard almost anything we have—wealth, health, possessions, time, status—and we do sometimes use the word jealousy in those contexts. But the term is most commonly associated with romantic and sexual relationships. Which makes good sense, since that's probably where the emotion first evolved—and where it still wreaks the most havoc.
Jealousy, evolutionary psychologists posit, is an evolved mechanism—one that developed to protect reproductive interests. And like so many evolutionary stories, this one diverges by gender. For men, the key un-certainty is paternity: whether the child they're raising is genetically their own. A partner's sexual infidelity, in this view, represents a reproductive threat, something to guard against. For women, who have no such uncertainty, the evolutionary risk is different: being left to raise a child without support. For them, the greater fear is emotional infidelity – a sign that a partner may be pulling away, investing elsewhere, or preparing to abandon the family unit.
This theory leads to a striking and testable prediction: that men should be more upset by sexual betrayal, and women by emotional betrayal. And considerable research supports such a view. In an early study, the American sexologist Alfred Kinsey and his colleagues found that 51 percent of divorced men said their partner's sexual infidelity played a major role in the breakup, compared to just 27 percent of divorced women—even though the men were twice as likely to have committed adultery. Later studies have tended to reproduce the finding.
For example, the psychologist David M. Buss and colleagues presented participants with hypothetical scenarios about sexual versus emotional in-fidelity and observed the same pattern as seen in the Kinsey survey: men reacted more strongly to sexual infidelities; women to emotional ones. Robert Pietrzak and coauthors took it a step further and measured physiological responses (e.g., heart rate and sweating) to infidelity scenarios, and again men showed stronger reactions to sexual infidelity and women to emotional infidelity.
Other differences by gender seem to reflect similar evolutionary pressures—though not all of these align neatly with the theory. Men, for example, are more likely than women to feel threatened by a rival's wealth or status. Women are more likely to be distressed by a rival's youth or physical attractiveness.
While evolutionary psychology may tell us something about the kind of jealousy men and women feel, it doesn't fully explain why some people are just more jealous than others. That question was at the heart of a large study of Finnish twins designed to tease apart nature and nurture in romantic jealousy. The researchers studied over a thousand twin pairs, including identical (monozygotic) twins, who share 100 percent of their genes but often end up in very different romantic situations. The logic was simple: If jealousy is mostly biological, then identical twins should have similar jealousy levels regardless of their experiences. If it's shaped more by the twists and turns of life, then their individual relationships—who they dated, how secure they felt—should matter more.
They found, first, that men and women did not differ much in overall jealousy. Women scored higher, but gender was by no means the best predictor of jealousy. About 29 percent of the variation in jealousy was attributable to genetic factors (inferred by comparing how similar jealousy scores were among identical versus fraternal twins). But the remaining 71 percent came down to non-shared environmental influences—presumably, at least in part, the personal, relationship-specific experiences unique to each twin.
What were those experiences? The study highlighted several, including whether they distrusted their current partner, whether they'd been "cheated on" in the past, and whether they felt they were dating "up" (meaning they believed their partner was more desirable than themselves). All these factors strongly predicted jealousy.
As important as relationship dynamics and someone's own romantic history are in determining feelings of jealousy, sometimes the seeds are planted as far back as childhood. One female respondent to the Misery Survey described her jealousy as so consuming it bordered on paranoia. "I am highly jealous and something as simple as a text, phone call, or email can set me off." Although, to her knowledge, she had never been cheated on, she couldn't shake the belief that an act of infidelity could happen at any moment. "I simply do not trust that this could not happen to me." This respondent traced her own jealousy not to personal betrayal but to the betrayals she had witnessed as a child: "I believe it occurs due to my mom and dad divorcing when I was five, and his new wife, my stepmom, used to be my mom's best friend. Growing up, most betrayals came from people who were either family members or good friends."
Only after twenty years of marriage did the feeling begin to loosen its grip, thanks in part to the sense of (seemingly problematic) control she had established in her relationship. Her spouse worked from home. The respondent had "full access to everything," so there was "no way they could cheat."
Naughty or Nice
Research by psychologist Jeremy Dugosh suggests that, in some relationships, a bit of jealousy may actually be a good thing. Dugosh studied 134 undergraduates at the University of Texas at Arlington, all of whom were in committed heterosexual relationships. He rated them based on standard psychological measures for romantic love, jealousy, and overall relationship satisfaction. The results were revealing: among participants who reported strong love for their partner, higher levels of jealousy were actually associated with greater satisfaction. In small doses—and in strong relationships—jealousy may reinforce a bond.
But that "sweet spot" is very small indeed. Across the full sample—including the less satisfied couples—Dugosh found that people who reported more jealousy also tended to report less love. Which suggests that outside of that narrow band—where love is high and jealousy is mild—the emotion begins to chip away at the very foundation it's trying to protect.
David Hume understood this very well. He conceived of jealousy as a "subordinate passion" that could sometimes support a romantic relationship—but once it rises past a certain point it "swallows up the affection it before nourished and increased. Too much jealousy extinguishes love."
Because jealousy is often a self-defeating emotion—one that leads us to do things that damage, and sometimes destroy, the very relationships we want to protect—it often gives way to regret . . . another misery, which we'll get to shortly. For now, I'll leave you with this—one of the more devastating responses I received from the Misery Survey, submitted by a man reflecting on an experience of jealousy from more than fifty years ago. In its quiet way, it strikes me as just as tragic as the fates of Othello and Desdemona:
When I was a freshman in college I met my first real "true love." She was a sophomore who actually picked me up at a party. For about two months we were inseparable, making love at every occasion, going places together, even going through the shock of thinking she was pregnant that turned out to be a false alarm. The intensity was both thrilling and unnerving. I traveled with her back to her home-town just before Thanksgiving to meet her high school friends. We went to a party. There I felt she was ignoring me, flirting with her old flame, and I became enraged with jealousy, even leaving the party and hitchhiking back three hours to school. After Thanks-giving she broke up with me and I was heartsick. She decided it was best to change schools and over Christmas transferred across the country to Arizona. In early January she fell off a horse, rupturing her spleen and suffering massive injuries. Her family chartered a plane and was flying her home. She died en route. Her sister told me during the flight she kept calling my name. I have never been jealous again.
- From The Opposite of Happiness by George Loewenstein, published by William Collins on 24 September.
SOURCE:
https://www.bps.org.uk/psychologist/jealousy(accessed 29.9.26)