Prince Harry and Prince William share an undeniable life-long bond, but that's not to say the pair don't have their ups and downs.
In fact, Harry himself has not held back from letting people know that things aren't always smooth sailing between the pair, even admitting in an unprecedented interview that this was the case.
And now, with the so called "rift" between the brothers more apparent that ever, another possible factor as to why it hasn't been resolved earlier has come to light.
In October, an explosive new documentary featuring Prince Harry and his wife Duchess Meghan aired on ITV.
The royals' raw, honest and at times, overwhelmingly emotional interviews featured in the doco, called Harry and Meghan: An African Journey, came as a confronting shock to the world.
And many couldn't get past a particular anecdote from Harry, who admitted that he and Wills hadn't exactly been seeing eye to eye.
"The majority of the stuff is created out of nothing but as brothers, you know, you have good days, you have bad days," he said.
In the interview, Harry explained that he and William were now on "different paths" and that they "don't see each other as much as we used to".
The 35-year-old added: "I will always be there for him as I know he will always be there for me."
As the world took in the emotional admission from Harry, it was natural for some to wonder how things could have gone wrong between the pair.
It is understood issues arose between them when William reportedly cautioned Harry about Meghan, telling him he might have been moving too fast.
In a new report from PEOPLE, it has been revealed that there was someone who could have helped smooth things out between the pair at that time, but he left the Palace just as it would likely have been coming to a head.
Indeed Christopher Geidt, who was the Queen's long-time private secretary, departed his role in 2017 - around the time Harry and Meghan's relationship was taking off, and likely around the time Wills reportedly issued his caution to Harry.
He is understood to have been a renowned peacemaker in the Palace, having smoothed over a lot of grievances between the two brothers and other family members.
A friend revealed to the publication that he "really had the boys backs".
According to the friend, there is still a strain on the brothers' relationship now.
"There is a lot of hurt and a lot of unresolved issues between the boys," they said, adding: "And no one to help mediate."
The source continued to explain that "petty grievances" had the potential to become huge conflict between the royal offices if they are not managed correctly.
"And that's exactly what's happening now," they said.
WATCH: Prince Charles, Wills and Harry arrive at the Our Planet premiere. Story continues after video...
It also pays to note that the boys are on quite different paths now, with Wills and Kate ramping up their work as they continue to prepare to become the future King and Queen Consort of England.
Harry and Meghan on the other hand, are now settling into their lives as new parents to baby Archie, who was born in May.
So with this in mind, one could argue any fallout between the pair is natural of any sibling relationship - let alone one that is constantly scrutinised by media.
And if there's one thing we'll always know for sure, it's this - Harry and William will always share an unbreakable bond, no matter what is thrown their way.