"From William's perspective, Harry really crossed the line," an insider told Us Weekly of the 37-year-old's latest endeavor. "The memoir feels like yet another dark cloud hanging over the monarchy as they wait with bated breath to see what bombshells Harry will drop next."
The dad-of-three "thinks his brother is out of his mind for writing a book on the royal family," another source dished. "He doesn't know who Harry is anymore."
The siblings, who have not been on the best terms in quite some time, do not seem to be making up any time soon, as Harry is "hardheaded and defiant," the insider noted. "Neither one of them will back down."
In 2021, the dad-of-two, who moved to California with his wife, Meghan Markle, in 2020, announced the big news. "I’m writing this not as the prince I was born but as the man I have become. I’ve worn many hats over the years, both literally and figuratively, and my hope is that in telling my story — the highs and lows, the mistakes, the lessons learned — I can help show that no matter where we come from, we have more in common than we think," he said in a press release. "I’m deeply grateful for the opportunity to share what I’ve learned over the course of my life so far and excited for people to read a firsthand account of my life that’s accurate and wholly truthful."