So just what happened at the end of The Paper Palace?

A book’s acknowledgements can be very telling. At the end of her debut novel, Miranda Cowley Heller tells another story: “When I was in my teens and first attempting to write fiction, my grandfather Malcolm Cowley gave me a piece of advice that I have carried with me: the only thing you need to know, he said, is that every good story must have a beginning, a middle and an end, with the end foreshadowed in the beginning.”

Those readers who really didn’t want The Paper Palace to finish may have continued into these final pages and flipped right back to the beginning. What Heller leaves us with, after all, is a delicious ambiguity: does our heroine Elle leave her husband Peter – a man she loves, the adoring father of her children – for Jonas, her childhood sweetheart, or not?

Miranda Cowley Heller, a debut author with decades of experience in storytelling (having worked as a books editor and as Head of Drama Series at HBO), deploys the pacing and plot of a binge-worthy box-set, with writing that immerses you in the cool ocean waters of Cape Cod. No wonder The Paper Palace has won accolades from literary giants such as Meg Wolitzer, Nick Hornby and Nina Stibbe.

But the same question that Elle poses throughout the novel – a choice, between Peter and Jonas – remains at its end. The pond that she swims in during the novel’s opening pages remains her morning ritual at its end. Only, this time, Jonas is on the shore. The ending leaves just enough open to question that while Heller admits she never intended to make the ending ambiguous, she has been pleasantly surprised by how many readers “have been debating the Jonas vs. Peter ending” – something she says is “great and interesting.”

In the wake of the book's released, the debate over the ending has become increasingly feverish. There are entire forum threads dedicated to it, in fact, on Reddit and Goodreads, with many people asking the same question: who did Elle choose?

Interestingly, the decision wasn’t always clear-cut for Heller, either. “I didn't have any idea who Elle would choose. In fact, the choice was made in the last two, three pages of the novel. It was very important for Elle not to be 'directed' by me but to live out the process organically.”

Heller followed her grandfather’s advice: throughout the novel, the pond remains a tether for Elle, for her family and her lovers. Her choice – and the dilemma it causes – is painted through the landscape like salt spray. In the hours after her infidelity, Elle treads a fine balance between craving the safety of the shallows (what Peter offers) and her “love” of “the fear, the catch of breath in my throat” (which Jonas provides). We just don’t know which she chooses.

There are clues, and potential red herrings, woven throughout The Paper Palace. The entire novel dwells on marriage and its frailties. Unhappy marriages run their way through the book as they do Elle’s heritage: her grandparents married three times a-piece; her mother Wallace had reams of lovers; her father had three wives. “In my day, we simply divorced and remarried,” Wallace quips. “So much simpler. Refreshing, even. Like buying a new suit of clothes.” When she takes off her wedding ring – “I squeeze it tight against my life line one final time before leaving it behind me on the step and heading down the path to take my swim” – is Elle protecting it from loss, or walking away from her marriage?

If Elle were to leave Peter, she would risk subjecting her children to the turbulence and trauma that her own parents’ relationships inflicted on her childhood. And yet, Elle’s mother is the only person who seems to understand her predicament. Early on, Elle tells the reader “the best lesson my mother ever taught me: there are two things in life you never regret – a baby and a swim.” In the novel’s closing pages, Wallace gives her some “serious advice”: “There are some swims you do regret, Eleanor. The problem is, you never know until you take them.” It suggests that Wallace is aware of Eleanor’s choice, and is telling her that while leaving Peter for Jonas may be a mistake, she’ll never know unless she does it.

When asked about the lesson of regret, Heller says it’s something that she heard “growing up on the Cape in the summers, something the grandmother of a friend had once said, and it’s always stuck with me.”

“Because for me, life always felt so messy and disorganised, and I love the idea of something that makes life feel so clear. Definitive. Crisp,” Heller continues. “And Wallace is declarative in that way. But also: I believe it's true.”

The seasons play a pertinent role in The Paper Palace, too. Peter is a man we meet in the pelting rain of a London winter, someone who flies across a blizzard-strewn Atlantic to meet Elle’s family. But Jonas belongs to the summer; big skies and salty air and pond swims. Peter wears beautifully made shoes of worn leather; Jonas is usually barefoot. One man she sees all year, the other only for a season. And yet, as she explains at the novel’s end, the summer retreat where she and Jonas met “is in my bones”. The Paper Palace withstands time: “the difficult, lonely winters; always threatening to fall into ruin, yet still standing, year after year, when we return”. Elle's relationship with Jonas, Elle suggests, as she has done throughout, is far more than some adolescent summer fling.

Heller says that associating the two men with place was more about “how place can ground us and shape us.” What was more important to her, though, “was the notion of choice, of the big or tiny moments that can completely change the direction our lives take. In Elle's case she is choosing between a great love and a great love. There is no bad choice, but that also means there is no good choice. And Elle does have to choose. So, understanding how she got to this impossible crossroads over the course of 50 years, and then seeing how her decision unfolds and unravels was definitely an idea that steered me.

So what are we to make of it all? One Reddit user, loyallong86, cannily went back to the beginning of The Paper Palace after reading it and re-read the book, skipping the flashbacks and piecing together only the present-day events that make up Elle's 24 lifechanging hours. Their conclusion? "Elle's choice is clear as she gets in the pond" (you can read the full breakdown here).

Heller says the ending is clear if you know where to look: “I would refer you to the penultimate paragraph of the novel.” Perhaps what The Paper Palace’s ending shows us is that, when we really connect with a book’s characters, it’s not always easy for us to accept the decisions they make.