Speaking with People magazine, a royal source explained that, with Philip out of action, the Queen is feeling incredibly overworked.
"She is always head of country and Prince Philip was always the head of family," the insider said.
"He is not there to be that - so everything is falling on to her shoulders. It must be an incredibly lonely place to be."
Prince Philip was taken to King Edward VII hospital back in February after "feeling unwell".
In a statement, Buckingham Palace said: "The Duke's admission is a precautionary measure, on the advice of His Royal Highness's Doctor, after feeling unwell.
The Duke was then transferred to St Bartholomew's to undergo a heart procedure, before being discharged on March 16th.
“The Duke of Edinburgh has today been discharged from King Edward VII’s Hospital and has returned to Windsor Castle, following treatment for an infection and a successful procedure for a pre-existing condition,” a palace spokesperson said.
It's been alleged that, while in hospital, Philip called on his son Prince Charles to discuss the future of the monarchy.
Speaking on The Royal Beat, former press spokesman for the Queen, Dickie Arbiter, claimed that Philip would have wanted to speak to his son to “to lay the ground”.
“I think it was at the request of the Duke that the Prince of Wales visited,” Dickie told Royal Beat host Kate Thornton and the other experts.
He continued: “To lay the ground. Look the man is 99, he is in with an infection. My guess is that he will come out, he will walk out and he will go back to Windsor.
“But eventually he is going to die and he was just saying to Charles, ‘one day you are going to be the leading man of the family’,” he added.