Prince Harry's reckless spending was said to be a factor in his rift with his older brother, Prince William.

According to "Royals at War," a book written by investigative journalists Dylan Howard and Andy Tillett, they claim that the Duke of Sussex's "spending transformation" was one of the "fundamental factors" behind the deep crack that opened between him and Prince William. 

Per the authors, Prince Harry spent $7,300 months before their wedding for acupuncture as part of a "health drive." 

Aside from the "wellness splurge," which included massages and aromatherapy, Meghan Markle also spent around $490,000 on maternity clothes. 

With the Duchess of Sussex spending so much cash, it rang alarm bells with Queen Elizabeth II, who grew up conservative. 

"Growing up in the war left the monarch with a built-in sense of frugality and economy despite being one of the world's richest women," an insider told Tillett and Howard. 

Meghan Markle and Prince Harry have also said to have enjoyed a "babymoon" at Heckfield Place, a luxurious spa in Hampshire. The couple stayed there for three nights, and the damages were around $40,500. 

When moving into Frogmore Cottage, they spent almost $3 million of taxpayer's money on refurbishing their home, which they later vowed to pay under Megxit terms. 

Kate Middleton Worries for Prince Harry

Everybody in the royal family was concerned when Prince Harry was in a rush to marry American actress, Meghan Markle. Everybody, especially his sister-in-law, Kate Middleton. 

The authors further claimed that the Duchess of Cambridge urged Prince Harry to take things slow with his girlfriend because it would take "time, care, and attention" for the actress to integrate with the family.

"She gently reminded him that he was dating someone with a completely different life, past, and career, and it would take some time, care and attention for them to integrate," the authors wrote. 

But all concerns were thrown out of the way because in May 2018, Prince Harry married Meghan Markle. 

Since then, the Duke of Sussex's relationship with the Duke and Duchess of Cambridge is broken, especially after Prince Harry and Meghan Markle moved to the US with their son, Archie.

Prince William's Well-Intended Concern

Aside from Kate Middleton's warning, Prince William also had concerns of his own that he told Prince Harry about it. 

According to royal insiders who told the authors, the Duke of Cambridge took his brother to the side and asked him, '" Is she the right one?'" just after meeting her. 

The book claims that, though Prince William's intention was good, Prince Harry didn't like how it looked and meant.

The Duke was even convinced that the royal family and the palace aides were so against him and his then-girlfriend.

But the feud would have been avoided, said Tillett and Howard, "if only Prince Harry were able to empathize and take his brother's concerns in the spirit that they were intended."

Prince Harry Sees Princess Diana in Meghan Markle

"Royals At War" also revealed that the only reason why Prince Harry is so drawn to Meghan Markle is because of her "confidence, commitment, drive and ambition," just some of the characteristics that his mom, Princess Diana, had. 

Tillett and Howard disclosed that subconsciously, the Duke of Sussex, was seeking a figure that would replace his mother. 

A source told the authors, "Harry feels he couldn't protect his mother, so he's going all out to protect his wife. He is so sensitive he often sees criticism or negativity where there isn't any." 

READ MORE: Meghan Markle Not Allowed to OUTSHINE Prince Harry in Royal Family