"If no one has lived romantic aspirations as intensely as Emma, in Flaubert's Madame Bovary, many people have at some time experienced a penchant for 'Bovarism', perhaps only deep within themselves," the future President wrote.
Bommel says she wrote the book because: "I wanted to understand how a woman from the provincial petite bourgeoisie, educated by nuns, had the incredible audacity to defy her family and popular morality to make a second life with a man 24 years younger."
When Macron joined Brigitte's drama club, she had been married to Andre-Louis Auziere, a banker, for nearly two decades. Two years her senior, he is shown in Bommel's book to be intelligent and kind, but dull, like Monsieur Bovary.
The now reclusive Auziere, who is not known to have remarried, has never commented publicly about his ex-wife or Macron. Tiphaine, the younger daughter he had with Brigitte, said: "My father is very well, but he wishes to remain in the most complete anonymity."
Like her siblings, Tiphaine, six years younger than Macron, gets on well with the President, who appears delighted to play step-grandfather to their children. Tiphaine even stood as one of his party's candidates in the 2017 election.
When Brigitte met Macron, her son, Sebastien, was slightly older than him and Laurence the same age. But he has managed to forge a close relationship with them.
Macron's parents, alarmed by what they viewed as an inappropriate relationship, swiftly packed him off to Paris to complete his studies, but he continued seeing Brigitte. He blames failing the entrance exam to the elite Ecole Normale Superieure two years running on being "too much in love to revise".
By now an arrangement had been devised that would keep family life on an even keel for everyone. Tiphaine said: "I was with my mother during the week and with my dad at the weekend, while Mum went to see Emmanuel."
Brigitte married Macron in 2007 in the same town hall in the seaside resort of Le Touquet where she married Auziere 33 years earlier.
Since taking up residence at the Elysee Palace, Brigitte has become France's "Kate Middleton", Bommel writes. Everything about her, from her slim figure to her clothes and diet — she breakfasts on "two kiwis and a cup of tea" — is dissected. But however she presents herself, she will never be able to truly escape the one question most people want to know the answer to: what made a married schoolteacher in her 40s embark on an affair with a teenager younger than her own son?
The book notes that the death of one of her elder sisters and her husband in a road accident, when Brigitte was 6, had a huge effect on her. "As she grew up, perhaps Brigitte deduced that she had to seize happiness before it ran away," Bommel suggests. Brigitte herself said in a 2017 interview: "If I hadn't made this choice [to leave Andre-Louis for Macron], my life would have passed me by."
Macron is said to be unusually faithful for a French President. Men who worked with him as economy minister recall sitting at a cafe when a bombshell blonde walked past.
All heads turned, except his. Anecdotes like this have fuelled rumours that Macron is gay, something he has denied and even joked about.
All those who have spent time with the Macrons say their affection for each other genuine. The fact that their pairing makes for one of the most unlikely love stories of our time simply makes it even more compelling to watch.
