The 92-year-old royal is reportedly smitten with the 36-year-old former actress, which has caused Kate Middleton to stir with jealousy, In Touch claims.
A source explosively told the publication, 'Kate feels left out.'
'Kate has spent years working on her image as 'the perfect royal', and Meghan is stealing her thunder,' the source added.
Now, In Touch reveals a war is brewing between the duchesses.
'They're barely on speaking terms,' the source says. 'The popularity contestant has caused a lot of friction at the palace.'
According to the US publication's bombshell claims, Kate feels 'betrayed' by the woman she had become close friends with - especially because it was Kate who helped Meghan ease into royal life before her wedding to Prince Harry.
'Meghan has learned everything from Kate. But since the wedding, Kate feels like Meghan has barely made any effort with her and is more interested in impressing the queen,' a palace insider tells.
Adding, 'In all fairness, Meghan has been busy. But Kate feels like she's put a lot of effort into their friendship and hasn't gotten much in return.'
Back before she was a polished princess, Kate had to figure everything out on her own.
It took five years of dating Prince William for Kate to meet Her Majesty, and it took another three before the palace started giving the Duchess of Cambridge etiquette lessons.
The boiling tension have reportedly gotten so bad, In Touch claims the two princes have been forced to intervene.
'William and Harry feel stuck in the middle,' a source tells. 'William is doing his best to smooth things over.'
'The competition is out of control,' adds the source. 'Things are likely to go from bad to worse.'
The royal family is yet to respond to In Touch's report.