It’s the question that keeps The Summer I Turned Pretty fans up at night. You know the one. Team Conrad fans point to it as proof of "fate," while Team Jeremiah fans usually just want to throw their remote at the TV. If you’ve been following the journey of Isabel "Belly" Conklin through Jenny Han’s trilogy—or the hit Prime Video series—you already know the vibe. Things get complicated. But when you really dig into why do jeremiah and belly break up, it isn't just about one single fight or a random moment of jealousy. It’s a slow-burn collapse built on grief, massive communication gaps, and a spring break trip to Cabo that changed everything.
Honestly, it’s heartbreaking.
The Cabo Factor: What Really Happened
Let’s get the elephant in the room out of the way first. The "cheating" controversy. During their second year of college, Jeremiah and Belly have a massive, explosive argument. It’s the kind of fight where things are said that you can't really take back. They "break up"—or at least, Jeremiah thinks they do. Belly thinks they’re just on a break. It’s very Ross and Rachel, but with more flip-flops and beach house trauma.
Jeremiah goes to Cabo for spring break. He’s hurting. He’s angry. And while he’s there, he sleeps with a girl named Lacie Barone from a different sorority.
When he and Belly get back together, he doesn't tell her. He lets her believe they were just "off" for a week and now everything is fine. The real reason why do jeremiah and belly break up eventually boils down to the fact that Belly finds out about Lacie from someone else. She hears it through the grapevine at a party. The betrayal isn't just the physical act; it’s the silence that followed. It’s the realization that their entire reconciliation was built on a lie of omission.
It Wasn’t Just About Lacie
If we’re being real, blaming the whole breakup on Cabo is a bit of a surface-level take. The cracks were there way before the plane landed in Mexico. Jeremiah and Belly were trying so hard to be the "easy" couple. They wanted to prove that they were better together than Belly and Conrad ever were. But you can't build a lifelong relationship on the sole foundation of not being someone else.
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Jeremiah always felt like the backup plan. That’s a heavy weight to carry. Even when they were happy, the shadow of Conrad Fisher was always loitering in the corner of the room. Jeremiah knew it. Belly knew it. Every time Conrad’s name came up, the vibe shifted. This insecurity made Jeremiah reactive. It made him feel like he had to compete for a space he should have already owned in her heart.
And Belly? She was young. She was grieving Susannah. She was trying to force a version of "forever" because she wanted the stability the Fisher family represented. Sometimes people cling to each other not because they’re the perfect fit, but because they’re the only ones who understand the specific shape of the hole in their lives.
The Proposal That Backfired
In a desperate attempt to fix the Cabo mess, Jeremiah proposes. Yes, while they are still in college. It’s a classic "band-aid on a bullet wound" move. He thinks that if they get married, the past won't matter. He thinks a wedding will prove to everyone—especially Conrad—that Belly chose him.
But the wedding planning only highlights their differences.
Belly realizes she’s doing all the heavy lifting. She’s domesticating herself while Jeremiah is still living the frat-boy lifestyle, relying on his father's money and not really showing up for the hard parts of adulthood. They’re playing house. The realization hits her at the motel and throughout the wedding prep: they are different people who want different things. Jeremiah wants to be taken care of; Belly wants to be seen.
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The Ghost of Conrad Fisher
You can’t talk about why do jeremiah and belly break up without mentioning the letters. Or the beach house. Or the way Conrad finally admits he still loves her right before the wedding.
During the wedding preparations, Conrad is around. He’s helping. He’s being the "good" brother. And in those quiet moments, Belly realizes that the fire she had with Conrad wasn't just a childhood crush. It was a deep, soul-level connection that she never quite found with Jeremiah. Jeremiah sees the way they look at each other. He realizes that even if they walk down that aisle, he’ll always be looking over his shoulder.
He deserves better than that. And so does she.
The Final Break: A Moment of Growth
The actual breakup is surprisingly mature compared to the rest of their relationship. They realize that getting married won't fix the underlying truth: they aren't each other’s "one."
Jeremiah finally accepts that he can't force Belly to love him the way she loves Conrad. He releases her. It’s a moment of sacrificial love that honestly makes Jeremiah a much stronger character than the "other brother" trope usually allows. He chooses his own dignity over a marriage that would have eventually ended in resentment.
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Belly, for her part, realizes she needs to be on her own for a while. She goes to Spain. She grows up. She learns who she is without a Fisher brother attached to her hip.
Why the Breakup was Necessary
- Trust was broken: The Cabo incident created a permanent stain on their transparency.
- Maturity Gap: They were trying to make adult decisions (marriage) while still acting like impulsive teenagers.
- The Conrad Factor: You can't marry one brother while your heart is still partially with the other.
- Identity: Both Jeremiah and Belly were defining themselves through their relationship rather than their own individual goals.
Actionable Insights for Fans
If you’re watching the show or reading the books for the first time, pay attention to the small details in Season 2 and 3. Notice how Jeremiah reacts when Conrad is mentioned. Watch for the ways Belly tries to convince herself she's happy.
The breakup isn't a failure. It’s a pivot. If you’re looking to understand the narrative structure, look at Jenny Han’s focus on the "growing pains" of young love. She doesn't write fairy tales; she writes about the messy process of leaving childhood behind.
To truly understand the dynamic, track these specific elements in the story:
- The frequency of mentions regarding Susannah’s wishes for them to be together.
- Jeremiah’s body language whenever they are at the Cousins beach house.
- The shift in Belly's internal monologue from "I love him" to "I have to make this work."
The end of Jeremiah and Belly’s romance is what allows them to eventually find peace as friends (or at least, as family). It clears the wreckage so that when Belly eventually reconnects with Conrad years later, she’s doing it as a woman who knows her own mind, not a girl caught between two brothers.
Check the specific scenes in We'll Always Have Summer where the couple interacts with their parents. You'll see that the pressure from the adults in their lives played a massive, often overlooked role in pushing them together—and ultimately, tearing them apart.