Meghan Markle felt "shunted off" when she was asked to stay in Nottingham Cottage and not Kensington Palace, it is claimed.
Author Tom Quinn said he believes the Duchess of Sussex would have initially been "drawn in" by the fantasy of the royal family.
But once she and Prince Harry settled into married life she became disappointed living "in a little cottage", he claimed.
Two-bedroom Nottingham Cottage was the couple's first marital home, located on the grounds of Kensington Palace.
Dubbed 'Nott Cott', it served as a base for the pair until their move to Frogmore Cottage - and later to California.
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Mr Quinn told the Mirror's 'Pod Save The Queen' podcast that he thinks Meghan's would have been unhappy with their first home.
"I think that actually, she wasn’t too keen on that," he said.
"It seemed like they were being shunted off to a little prefab in the grounds."
Harry had lived in Nottingham Cottage - described as "snug" - since 2013, with Meghan joining him just before their engagement.
But, contrary to Mr Quinn's claims, authors Carolyn Durand and Omid Scobie say Meghan was happy in the property.
Writing in 'Finding Freedom', and as reported by the Daily Express, they said: "After months of long-distance, Meghan was thrilled to finally be sharing a postcode, W8 4PY, with her partner.
"She felt at home at Nott Cott with Harry - she’s always been able to bloom where she was planted, but she hadn’t moved to London to start a new job.
"She had moved to London to start a new life."
But Harry and Meghan did not stay in Nottingham Cottage for long, and soon moved to Frogmore Cottage in Windsor - reportedly to get away from the pressures of life in London.
But Mr Quinn claims that too became an unhappy arrangement, as Meghan "suddenly realised it was like living in the Russian Steppe".
The author of 'Kensington Palace: An Intimate Memoir from Queen Mary to Meghan Markle' added: "She was away from everything."
The Sussexes have now settled in California, US, in a sprawling multi-million dollar mansion, after they quit royal life.
And, in February, when TV host James Corden joked that the pair should move into the lavish mansion from the sitcom The Fresh Prince of Bel Air, Meghan replied: "I think we’ve moved enough."
