Emmanuel Macron was 15 when he fell for his 39-year-old drama teacher, whose daughter was his classmate at the Catholic Providence school in Amiens, northern France.
The schoolboy’s parents had believed their son was dating his teacher’s daughter, Laurence, until the truth came out through a family friend.
Shocked at the illicit affair, the Macrons removed their teenager from the school and sent him to board in Paris.
In an interview with Paris Match magazine, she said she thought Mr Macron would move on when he was sent to Paris.
But while his parents hoped distance would cool the burning embers of passion, the young Macron vowed to marry the former Ms Auzière and held fast to his oath.
“For me, such a young boy was crippling. Emmanuel had to leave for Paris. I told myself that he would fall in love with someone his [own] age. It didn’t happen,” Ms Macron said.
The couple, with a 24-year age gap, married in 2007. Becoming a very youthful stepfather at the age of 29 to her three adult children, he told them at the wedding reception: “Thanks for accepting us, a not-quite-normal couple.”
Ms Macron said her children were the “obstacle” which caused her to wait a decade before marrying the president.
She said: “I took time so I would not wreck their lives. That lasted ten years, the time to put them on the rails. You can imagine what they were hearing. But I didn’t want to miss out on my life.”
Mr Macron has become France’s youngest ever President at the age of 39 – the same age as his wife, now 64, was when they met.
Praising her husband, the First Lady said his sharp intellect still surprises her every day.
She said: “I have never seen such a memory … such an intellectual capacity. I had many brilliant pupils and none had his capability. I have always admired him.”
Many commentators have said the obsession with their age gap is an example of deeply ingrained misogyny since men in positions of power are frequently married to much younger women.