Kate Middleton was so worried about Harry and Meghan's relationship, she pulled her brother-in-law to one side and told him to slow his relationship with the former Suits star.
A new book, Royals At War, about the Royal Family by royal investigative reporters Dylan Howard and Andy Tillet reveals that the Royal Family were so concerned about Prince Harry rushing into getting married to Meghan Markle, that even Kate told him of her fears.
The book says that Kate is the only one who knows about the dangers of marrying into the Royal Family after coming from a 'common' background.
She said she wanted Meghan to slowly adjust to her new life by seeing the realities of becoming a royal over time.
She told him to take things slowly, because it would take "time, care and attention" for "completely different" Meghan to become part of the family.
The book says, “She gently reminded him that he was dating someone with a completely different life, past, and career and it would take time, care and attention for them to integrate.”
Before his marriage to Meghan, the Duke of Sussex was very close to Kate, and even referred to her as "the big sister I never had".
Royals At War also reveals that Prince Harry's brother Prince William also tried to talk to him about his relationship with Meghan asking, "Is she the right one?" shortly after meeting her, according to insiders.
However, Kate and William's concerns didn't have the desired effect and Harry became convinced that the Royal Family and palace aides were working against Meghan, even though many palace staff say that was never true.
"The rifts that eventually opened up in the Royal family after Meghan arrived could have been avoided if Harry was able to empathise and take his brother's concerns in the spirit they were intended."
Harry then fell out with Prince William and then announced he was stepping back from the Royal Family to start a new life in America with Meghan and his one-year-old son, Archie.