Prince William and Prince Harry (opens in new tab) were still very young when their parents, Prince Charles and Princess Diana (opens in new tab), divorced. The divorce of Prince Charles and Princess Diana (opens in new tab) was very acrimonious and shaped how Prince William and Prince Harry thought about marriage as adults. But the divorce did not shape them in the same way.

In his new book, "Battle of the Brothers: William and Harry: The Inside Story of a Family in Tumult" (opens in new tab), royal biographer and historian Robert Lacey writes that Prince Charles and Princess Diana's dramatic divorce, William and Harry (opens in new tab) affected them differently, and how those differences led to their current feud.

"We thought the disorder, chaos, and tragedy of the 80s and 90s was over for our parents. Now it has come back in the form of these two boys. They are the legacy of all that heartache," Lacey recently said, according to Page Six (opens in new tab). 'They both talk about the importance of mental health and admit they are mentally fragile. But they both dealt with it in different ways."

For Will, the lesson of his parents' divorce (open in new tab) was to make sure he never had to go through the same situation. Because his mother was thrown into the royal world so quickly and felt as if her marriage was doomed from the start, he was careful not to make the same mistake in his own marriage.

"When he met Kate Middleton in college, he actually made the poor young woman wait nine years to virtually audition her for a job as the wife of a head of state. He learned his lesson of duty," Lacey explained of Will's reaction to the trauma of his parents' divorce.

Harry, on the other hand, seems to have a different interpretation of the causes of his parents' divorce and was never really in love in the first place (Prince Charles was famously still obsessed with Camilla Parker-Bowles (opens in new tab), with whom he had an affair and eventually married (they would eventually marry).

"His attitude," says Lacey, "was, 'I don't want to make the same mistakes my parents made. I'm marrying for love.' And he is very happy and proud, declaring that he has loved Megan virtually from the moment he met her in 2016. That impulse has guided him."

According to Lacey, these very different approaches to love fueled the brothers' feud.

"The rift gets worse with each passing day," he says.