Meghan Markle "prepared herself for a grilling" before her first meeting with Prince William, who was "wary" of her intentions, it has been claimed.
And while that initial sit down is understood to have gone off without a hitch, the future King is said to be deeply upset by his sister-in-law's Oprah Winfrey interview.
The former Hollywood actress - who stepped down as a senior royal along with husband Prince Harry last year - made a number of damaging allegations to the US chat show host last month.
Royal sources have told commentator Dan Wootton that William will "struggle to ever forgive Meghan".
And a senior insider went on to allege that the "biggest strains now exist between William and Meghan", especially after the Duchess revived an argument with wife Kate during the bombshell interview.
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But their relationship had reportedly all begun on a much more positive note.
Royal correspondent Omid Scobie, who co-wrote Megxit biography Finding Freedom, said William had told Meghan on their first meeting: "I was looking forward to meeting the girl who has put that silly grin on my brother's face."
In the book, which Mr Scobie penned with Carolyn Durand, they claimed Meghan and William got "along so well" after that first meeting.
They said the Duchess had no doubt William would "want to know everything about her - and her intentions".
"She was self-aware enough to understand that the brothers were wary of women who were more interested in their titles than their wellbeing."
"Because of this, she had thought the entire meeting through, she told a friend," the authors added.
A confidante told them: "She prepared herself for a grilling."
However, William is reported to have voiced concerns about how quickly the relationship was moving to aides and allegedly told his brother in April 2017 to "take as much time as you need to get to know this girl".
Finding Freedom suggests Harry took this as a "snobbish" aside rather than his brother checking he wasn't "blindsided by lust".
Writing in his column for Daily Mail, Mr Wootton said a source said William became worried that Meghan was "more concerned about her personal progression or profile over the wider goals and aims of the Royal Family".
The Duke of Cambridge is said to have kept his feelings under wraps as best he could, taking into account the huge adjustment of entering the Firm.
However, he reportedly felt the handling of Megxit and the Oprah interview disrespected the Queen and the family.
