But back in 2010, as the second-in-line to the British throne geared up for a proposal to his long-time love, Prince Harry was reportedly "afraid of losing his brother".
The UK Express reports that royal expert and author Katie Nicholl investigated the private lives of the princes - who grew up exceptionally close under the harsh glare of the public spotlight after the untimely death of their mother, Princess Diana - for her 2017 book "Harry: Life, Loss, and Love".
In the revealing work, Nicholl laid bare the younger of Prince Charles' sons concerns about the couple's potential engagement writing: "Harry adored Kate, and while he feared losing his brother, he was genuinely delighted for them."
According to the author, Harry suspected an engagement was imminent when William and Kate travelled to Kenya for a romantic three-week safari.
"When William called to tell him the good news, Harry [told] his brother and soon-to-be sister-in-law 'It took you long enough!'"
Harry gave the couple his blessing by allowing William to give Kate Princess Diana's famous sapphire engagement ring, with the young prince - who had a burgeoning reputation as a party animal at the time - joking he had "no pressing need for it".
Seven years later, Prince Harry used diamonds from his late mother's collection to design an engagement ring of his own for Meghan Markle.
The Express report comes amid continuing denials from Kensington Palace about the existence of a royal rift between the princes and their wives.