The Sunk Cost Fallacy in Love: Why We Stay in Toxic Relationships— A Death on the Nile Psychological Analysis
March 30, 2025 | by Mindseek
The first time I picked up Death on the Nile, life got in the way. The second time, another distraction. But on my third attempt, the novel’s irresistible pull triumphed. I devoured it in two sittings, utterly captivated. Halfway through, I knew it would be my favorite Agatha Christie book, and by the time I reached the shocking yet inevitable conclusion, that feeling was justified.
It was a real page-turner—filled with glamour, passion, and suspense—but beyond its thrilling plot, Death on the Nile contains a profound psychological lesson: why people stay in doomed love, even when every sign tells them to leave.
As I turned the final page, Poirot’s last words lingered:
“It is not the past that matters, but the future.”
And yet, for some, the past is an unrelenting chain.
Step Aboard the S.S. Karnak: A Love Triangle Destined for Disaster
The Nile stretches endlessly, gold-tipped waves shimmering under the Egyptian sun. As it glides across the water’s surface, the S.S. Karnak carries polished decks that witness whispered promises, stolen glances, and secrets that pulse with an undertow, waiting to drag lovers deep into the water.
At the center of it all is Linnet Doyle: radiant, envied, newly married, and uneasy.
Beside her is Simon Doyle- handsome and charming, but something stands between him and those things he won’t tell.
And then there is Jacqueline de Bellefort, watching from the fringes, her dark eyes burning with an emotion too intense to name. Love? Hate? Maybe both-maybe they are the same thing.
Love can be a beautiful dream. But sometimes, it is a slow, exquisite tragedy.
“Love can be a very frightening thing. That is why most great love stories are tragedies.”
As the steamer moves forward, so does fate. Three murders will stain the decks before the journey is over. But before the blood is spilled, before the gunshots echo, there is something far more insidious at play—the sunk cost fallacy in love.
Why do we stay in relationships that are clearly doomed? Why do we hold on to love even while being dragged to ruin?
The Sunk Cost Fallacy: Why We Cling to Doomed Love
In behavioral economics, the sunk cost fallacy refers to our tendency to continue investing in something—time, money, or emotion—simply because we’ve already put so much into it.
The sunk cost fallacy is simple: we keep investing in something—money, time, emotions—not because it’s good for us, but because we’ve already given too much to walk away.
This happens in finance. It happens in careers. But most painfully, it happens in love.
Each character in Death on the Nile falls victim to this psychological trap, but in different ways:
Jacqueline: She and Simon had already set their murderous plan in motion. Backing out would mean losing everything—the time, the risk, the dream of wealth. Even when the walls closed in, she clung to their plan, too far gone to turn back.
Linnet: She believed that if she gave enough, loved enough, and controlled enough—she could make Simon truly hers. But love cannot be bought, only borrowed.
Simon: One lie led to another, one crime demanded the next. Instead of stopping, he doubled down on his deceit, unable to face the cost of admitting his mistakes.
And isn’t that exactly what happens in real life?
People stay in unfulfilling relationships, dead-end jobs, or toxic friendships simply because they’ve already poured too much of themselves into them. Walking away feels like failure, but staying is the real tragedy.
“It is only when we are young that we think love is everything.”
Real-Life Takeaway: Are You Holding Onto a Relationship Because of Investment—Not Happiness?
Have you convinced yourself that you’ve been with someone too long to walk away now?
Are you trying to fix a relationship simply because you’ve already put so much effort into it?
Do you fear leaving will make all your sacrifices feel wasted?
Recognizing this mental trap is the first step toward breaking free.
The “Fey” Effect: That Strange Happiness Before the Fall
There’s a moment before disaster—a fragile, eerie calm. Poirot calls it being “fey.”
“Fey…a Scotch word. It means the kind of exalted happiness that comes before disaster. You know—it’s too good to be true.”
Jacqueline exhibits this phenomenon. She appears almost serene before pulling the trigger on Simon’s leg, her eyes alight with something otherworldly. Was it madness? Or had she simply accepted her fate?
Psychologists recognize this as the “last hurrah” effect—a final burst of euphoria before impending doom. It’s seen in people about to make catastrophic decisions:
A gambler places their biggest bet, knowing they’ll lose.
A failing business pours money into one last risky venture.
A toxic couple experiences one last blissful moment before everything crumbles.
But beneath that deceptive calm, something deeper is at play:
Cognitive dissonance resolution – When reality contradicts our desires, the brain chooses peace over truth. Jacqueline could not escape her doomed path, so she embraced it instead.
The self-fulfilling prophecy – When you believe something bad will happen, you may act in ways that ensure it does. She had always said she would kill for love—was this, in the end, simply making good on her own tragic promise?
Perhaps Jacqueline’s “fey” moment wasn’t peace—it was resignation. She had followed the plan to its bitter end, and there was no escape now.
And isn’t that how many relationships end? Not with a fight, but with quiet, exhausted acceptance.
The Moment of No Return: When Walking Away Is the Only Option
Every character in Death on the Nile had a chance to walk away.
Jacqueline could have let go of Simon before she crossed the point of no return.
Simon could have chosen honesty over greed.
Linnet could have recognized that no amount of wealth could manufacture love.
But they didn’t—and it led to ruin.
What stops us from letting go, even when we know we should?
Cognitive dissonance: We convince ourselves it will work out because facing the truth is too painful.
Loss aversion: We fear losing what we’ve already invested more than we desire a fresh start.
The illusion of control: We believe we can “fix” things, even when the foundation is already cracked.
But there is always a moment to walk away—if we are brave enough to take it.
How to Recognize Your Own Point of No Return
Are you ignoring red flags because you’ve already invested so much?
Do you feel a strange calm about something you should be afraid of?
Are you making excuses for a relationship that drains rather than fulfils you?
Identifying these signs can save you from falling into your own doomed love story.
Poirot’s Final Wisdom: Choosing the Future Over the Past
In the end, Poirot, ever the wise observer, leaves us with a truth that extends beyond murder mysteries.
“It is not the past that matters, but the future.”
The sunk cost fallacy convinces us that walking away is failure. But staying in something that is already lost—that is the real failure.
Simon and Jacqueline clung to their sunk costs—their scheme, their lies—until it consumed them. But we don’t have to make the same mistake.
Letting Go Isn’t Losing—It’s Winning Back Your Future
Love should make you grow, not shrink.
You are not obligated to stay in something just because you’ve invested in it.
The pastis already spent—the future is still yours to claim.
If you find yourself holding on to something that’s already slipping away—a love that no longer loves you back, a dream that’s turned into a burden—ask yourself this:
Are you staying because it’s right, or because you’re afraid of how much you’ve already lost?
Because sometimes, the bravest thing you can do is let go.
🚢💔 If you’ve ever found yourself trapped in an unhealthy emotional investment, share your thoughts in the comments below. Let’s start a conversation. And if you know someone who might need to read this, send it their way!
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