According to a royal biographer, Prince Philip is "very, very disappointed" by Meghan Markle's failure to "support the monarchy" and Prince Harry.
The 99-year-old Duke was well known to have given up his career in the navy in 1952 to support the Queen when she took the throne.
Philip is said to have been irritated that the Duchess of Sussex failed to do the same.
Ingrid Seward, speaking to Sky New, said Philip couldn't understand why the former actress didn't follow his example when she married Prince Harry in May 2018.
"I think he's very, very disappointed because I think he feels he gave up his naval career in order to stand by the Queen and help the monarchy," she said.
"And why can't Meghan just give up her acting career, support her husband and support the monarchy?
"As he used to say to Diana, this is not a popularity contest, this is all of us working together.
"He just cannot understand why she couldn't support Harry and help him rather than wanting to have her voice."
Steward said Philip didn't want to be a part of the talks about the Sussexes' future outside the monarchy, which was held at Sandringham in January.
Steward also claimed the Duke of Edinburgh doesn't wish to get involved any more since Prince Harry and Meghan officially stepped back from the Royal Family in March this year.
"Of course, it irritates him hugely. And when they had the Sandringham Summit, Prince Philip was seen leaving the house very swiftly before they all arrived," she observed.
"He simply doesn't want to get involved any more."