The religious ceremony took place when they turned 13, but when the time came to consummate the marriage at the age of 18, Modi refused and left his home town of Vadnagar after a family row.
Jashodaben became a teacher, working in a mostly Muslim village until she retired three years ago.
Her niece Nirali told GlobalPost: "She is a very religious woman. She likes simplicity and modesty."
And despite her husband's success, she is eager to remain a private person. "We have had lots of people come here, even Rahul Gandhi's personal adviser, but she doesn't want to talk to any of them," said the niece.
Narendra Modi's family is just as reluctant to talk. His elder brother Somabhai agreed to meet GlobalPost after we spoke by phone, but was nowhere to be seen when the time came.
By the age of 18, Modi had joined a right-wing Hindu organization called Rashtriya Swayamsevak Sangh, a movement founded in 1925 during Indian resistance to British rule.
The RSS was banned temporarily after former member Nathuram Godse assassinated Mahatma Gandhi in 1948. By the 1980s it had become mainstream and was the driving force behind the newly formed BJP.
Nilanjan Mukhopadhyay, the author of Narendra Modi: The man, the times, said: "The rules of the RSS did not allow Modi to marry.
"He was a pracharak, a propagandist who lived and worked for the RSS full time. If he had admitted the marriage, he would have lost his position."
But Modi is highly sensitive about the marriage. He was upset enough to personally intervene when Indian journalist Darshan Desai investigated Jashodaben's story after the 2002 riots.
Desai managed to meet the ever-loyal Jashodaben in her village, only to receive a phone call from Modi who accused him of having an agenda and going "much beyond" even the worst accusations against him about Godhra. Desai has admitted he felt "nervous" about the phone call. He confirmed the incident to the GlobalPost but declined to add details.
The celibate servant
In fact, Modi appears to be proud of his status as a single man, and uses it as a political tool.
Kingshuk Nag quotes Modi in his biography "The NaMo Story" as saying in a political speech "I am an honest man, vote for me. I cannot be dishonest. I don't have family to look after."
"People in India believe politicians become corrupt because they are under pressure from their wife or their mother or their brother or sister," Nag said. "He often makes this comment in his speeches."
There is a Hindu tradition of Indian men turning their backs on family to devote themselves to a cause, Nag added, which means voters do not view his single status with the suspicion that a politician in the West might encounter.
Modi's success as Gujarat's chief minister since 2001 is often described in business terms - unsurprising for a man who is feted by billionaires such as Mukesh Ambani and Ratan Tata.
He starts work at about 6 a.m., far earlier than his predecessors, and is renowned for his ability to grasp the finer details of government affairs.
"He is an extremely efficient service provider, the finest CEO this country can have," his biographer Nilanjan Mukhopadhyay said. "He is a most competent manager and an extremely organized delegator of authority.
"He believes he has a god's gift. He told me he gets sudden flashes of brilliance and tells his staff to implement his ideas."
A cult following
But Modi's electoral success is not only about his organizational skills. He does not simply have supporters - he has devotees.
About 100 fans came to watch Modi open a new park in Ahmedabad earlier this month. One covered his clothes in badges featuring the politician's face.
They call him "NaMo" - not just a J-Lo-style nickname but a Gujarati word that means both "hello" and "surrender" - and chant his name like a rock star.
