After over 70 years of marriage, Queen Elizabeth II and Prince Philip are still going strong. While there are probably a lot of factors that contributed to their long-lasting relationship, there's one moment in particular that gives the public a glimpse into what those are.

That one moment occurred in 2011 when Prince Philip celebrated his 90th birthday. However, it wasn't until after he retired from royal duties in 2017 that Daily Mail royal correspondent Richard Kay detailed the moment.

"Nothing illustrates the Queen’s devotion more than her marking his 90th birthday by bestowing on him one of her own titles, that of Lord High Admiral," Kay wrote, according to Express.

"Friends describe him as being 'almost in tears' at the gesture," he continued.

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To some, Queen Elizabeth just gave her husband a title, but it's the thought and meaning behind it that hit his heart. Lord High Admiral is the titular head of the Royal Navy, which is the career path Prince Philip wanted to pursue before marrying.

"I thought I was going to have a career in the Navy, but it became obvious there was no hope," he later recalled, according to Kay. "There was no choice. It just happened. You have to make compromises. That's life. I accepted it. I tried to make the best of it."

Surely, it's gestures like this along with some other shocking details about their marriage that help the royal couple stay strong over the year. For example, maybe it's the fact that they don't typically snuggle up in bed with each other at the end of the day.

"In England, the upper class always have had separate bedrooms," Philip's cousin, Lady Pamela Hicks, has shared.

"You don’t want to be bothered with snoring or someone flinging a leg around," she continued. "Then when you are feeling cosy you share your room sometimes. It is lovely to be able to choose."

Britain's Queen Elizabeth II and Prince Philip
Britain's Queen Elizabeth II and Prince Philip are photographed. AFP/Fiona HANSON