Prince Harry's relationship with Princess Eugenie is different from his relationships with his other royal cousins. The two are apparently close enough to be best friends and connect so well because of their similar personalities.

The bond between Prince Harry, 35, and Princess Eugenie, 30, is detailed in Finding Freedom, by authors Omid Scobie and Carolyn Durand. The York princess apparently thought that Meghan Markle is the "tonic" that her big cousin needed. 

Princess Eugenie was one of the first people to know that Prince Harry was dating the American TV star. It was also through her that Prince Harry met Cressida Bonas, his ex-girlfriend years before he met Meghan. 

The Duke of Sussex reportedly often seeks out his cousin when he has relationship issues. He likes that his younger cousin was wise beyond her years as she often dishes advice about his dating life. 

During their dating phase, Prince Harry and Meghan reportedly often went on double dates with Princess Eugenie and Jack Brooksbank. They also spent holidays together and once stayed at George and Amal Clooney's villa in Lake Como. Incidentally, Jack, whom Princess Eugenie married in the same year as the Sussex pair, works as a brand ambassador for the Clooney's wine brand.

However, some tension was said to have occurred prior to Archie's birth. Prince Harry and Meghan reportedly told people they were expecting their first-born during Princess Eugenie and Jack's wedding party. 

A source told the Finding Freedom authors that Princess Eugenie felt this was particularly off. She allegedly told a friend that the Sussex pair should have waited to share their good news instead of stealing the thunder on her wedding day. 

Dylan Howard and Andy Tillett, the authors of Royals at War: The Untold Story of Harry and Meghan's Shocking Split with the House of Windsor, also wrote a similar story about Meghan's baby announcement. They claimed that it was Meghan who made the call to announce the pregnancy to the Brookbanks' wedding guests, which allegedly embarrassed her husband.

Princess Eugenie's mom, Sarah Ferguson, was also apparently upset when the Sussexes made her daughter's wedding about them. Prince Harry and Meghan officially made the pregnancy public three days after the Brookbanks' wedding with a statement from Buckingham Palace. 

However, the Sussexes continued to hang out with the Brookbanks as married couples, suggesting that the social faux pas was water under the bridge. Princess Eugenie was apparently a frequent visitor of Frogmore Cottage, the Sussex pair's home in London, especially after Meghan had her first-born child, Archie Harrison.