Kate Middleton 'Treats Husband Prince William Like a Fourth Child Because He's Prone to Tantrums': Source

Even though Kate Middleton only has three kids, it seems like she thinks of Prince William as one of her own as well.

"Kate treats him [William] like the fourth child because he's prone to tantrums," a source told author Tom Quinn.

"They do have rows. It's not a perfect marriage. They have terrific rows," the author explained. "But, where some couples have a row and throw heavy vases at each other, William and Kate throw cushions at each other. It's always kept under control."

The royal family's motto is "never complain, never explain" — something the duo, who share Prince George, Prince Louis and Princess Charlotte, have followed.

"Because William adopts the manners and ways of behaving of his grandmother and Kate is very good at not complaining, both of them have stuck to the thing that made Queen Elizabeth II such a remarkable monarch," Quinn said. "They very rarely complain and when they do it's always in measured terms."

As OK! previously reported, William, 40, gets feisty sometimes, especially if he's around his father, King Charles.

"He can be difficult. He is a driven person and that can make him impatient. That can make William short-tempered when dealing with Charles," author Robert Jobson spilled. "The Boss (Charles) has a temper, too, but it does not go on and on. He can get frustrated and flare up and then, in an instant, it is forgotten about. With William, it is rarely forgotten."

In Prince Harry's memoir, Spare, he claimed he got into a physical altercation with his brother over Meghan Markle.

Harry recalled his brother grabbing "me by the collar, ripping my necklace, and he knocked me to the floor. I landed on the dog’s bowl, which cracked under my back, the pieces cutting into me. I lay there for a moment, dazed, then got to my feet and told him to get out."

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"I can pretty much guarantee today, that if I wasn’t doing therapy sessions like I was and being able to process that anger and frustration, that I would’ve fought back, one hundred percent," Harry said in an interview regarding the incident.

The Mirror reported on the comments about William.