The saddest part of Prince Harry's departure is not the moment he lost all the positions he had before, but the fact that he can no longer bring back the brotherly relationship he used to share with Prince William.

A royal insider opened up to People and said that the Duke of Sussex's relationship with Prince William became so stiff and strained that he cannot do anything to mend it in any way.

"They won't get back to the way they were," the source said. "Harry is looking straight ahead at his future with his family."

To recall, the once close brothers started to drift apart when the Duke of Cambridge advised him not to be "in a rush" in marrying Meghan Markle. But Harry refused to listen to him and married the Duchess of Sussex in May 2018 -- only two years since they met in London in July 2016.

Even royal expert Katie Nicholl revealed how Harry blamed his brother for not putting some effort to embrace Meghan in the family.

"Harry felt William wasn't rolling out the red carpet for Meghan and told him so. They had a bit of a fall-out, which was only resolved when Charles stepped in and asked William to make an effort," the royal author disclosed.

After they announced their decision to step down as senior members of the royal family, however, Harry received nothing but cold shoulders from Prince William.

Awkward Royals?

During the Commonwealth Day service at Westminster Abbey on March 9, the brothers showed a colder approach to each other in public.

The Duke and Duchess of Sussex sat in the second row behind Queen Elizabeth II, Prince Charles, Camilla, Prince William, and Kate throughout the service.

Although they came in earlier than Duke and Duchess of Cambridge, they still smiled and greeted Prince William and Kate. However, the Cambridges told them nothing but brief greetings.

According to the report of the Daily Telegraph, Harry was so surprised by William's "cold and perfunctory greeting."

"He literally said: 'Hello, Harry,' and that was it and he didn't say anything more than that," Harry allegedly told his wife.

Massive Royal Mistake

​Their relationship could have been fixed, but they never got the chance to hear the words from Christopher Geidt, Queen Elizabeth II's former long-standing secretary.

In July 2017, Her Royal Highness allowed Charles, Prince of Wales, and Andrew, Duke of York, to remove her most trusted aide, Sir Geidt -- or Lord Geidt as what the royals called him before.

He played a key role in the monarchy, as he was known to be that staff to whom royal family members listen to. He could have helped Princes William and Harry to smooth their grievances toward each other.

For instance, he somehow helped the two in fixing their relationship with Prince Charles.

"Petty grievances can become huge conflicts between all the different royal offices if they aren't managed correctly, and that's exactly what's happening now," a friend of the two royals told People.

Since Harry and Meghan will no longer be working royal members starting next month, the duke will also lose the chance to try fixing his relationship with Prince William for the last time.

READ MORE: Royal Regret: Mourning Prince Harry NOT YET Ready to Give Up Royal Life