While the Queen has described her husband as her "strength and stay," the pressures of royal life are likely to have taken a toll on their relationship.
It's widely known that the royal couple moved to Clarence House following their royal wedding on November 20, 1947.
Lady Pamela Hicks, a cousin of Prince Philip, told royal author Sally Bedel Smith that the couple had connected bedrooms, as opposed to sharing a master suite.
"In England, the upper class always have had separate bedrooms," she explained, adding, "You don’t want to be bothered with snoring or someone flinging a leg around."
"Then when you are feeling cosy you share your room sometimes. It is lovely to be able to choose."
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Her Majesty and the Duke of Edinburgh also do not engage in public displays of affection.
However, Myka Meier - an expert in royal etiquette - toldPeoplethat there were no formal rules on royal couples being romantic in public.
"Senior members of the royal family would likely not be told how to interact or when they can or can not show PDA and would be trusted to use their better judgement as to when it’s appropriate," she said.
"The royals often adjust PDA to mirror the formality of the event they are attending.
"At a sombre or more formal event, we are less likely to see PDA than at a casual event where it would be deemed more fitting."
Her Majesty and the Duke of Edinburgh do not engage in public displays of affection.
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In particular, Meghan Markle and Prince Harry appear to be unafraid to hold hands and embrace in public.
Meghan Markle and Prince Harry were seen holding hands on their trip to South Africa.
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However, Prince William and Kate Middleton have followed in the footsteps of the Queen and Prince Philip by keeping their public displays of affection to a limit.
One of their only public kisses were on the balcony of Buckingham Palace on their wedding day.
