Like all new parents, Prince William and Kate Middleton are smitten with Prince Louis. "William is constantly getting up in the night to check on the baby. He can’t take his eyes off of him," a royals insider tells Closer of the newborn, who made his grand entrance into the world on April 23.

The late-night lovefests clearly took a toll on the proud dad, however, as he was caught nodding off during a public Westminster Abbey ceremony a couple of days later! But who can resist the charms of the youngest royal, who weighed in at 8 lbs., 7 oz. after Kate delivered him at 11:01 a.m.

"William and Kate have never been happier," the insider says. Even Queen Elizabeth, 92, who met her newest grandchild on April 26, was beaming with excitement. "The queen doesn't usually get emotional, but as soon as she held the baby her eyes welled up with tears of happiness," the insider reveals, noting that the prince is said to be "a real Windsor," in that he looks like his father's side of the family. "She adores him!"

The same goes for siblings Prince George, 4, and Princess Charlotte, who just turned 3. "They're both thrilled to have a new brother. They love cuddling him," the insider notes, adding that Kate is "bonding with the baby and ensuring her children are adjusting to any changes at home."

Kate, who returned to royal duties just six weeks after having George, has reportedly lined up at least six months of maternity leave to guarantee everyone's as happy and rested as can be.

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Princess Charlotte and Prince George arrive at the hospital to meet Prince Louis.

That's especially important since William, 35, and Kate, 36, feared Charlotte might give them some trouble when it came to abdicating her title as the youngest royal. "There are times she acts jealous and demands attention while Kate is nursing the baby," the insider shares, so the doting mom planned an extra special May 2 birthday celebration for her daughter.

"Kate bought her all her favorite toys, Disney costumes, and a new outdoor swing, and slide," the insider shares. The plan seems to have worked, as Charlotte's been "treating the baby like a doll, and William and Kate always help her to hold him as she giggles."

George is equally as taken with his new sibling. "He always wants to hold his hand and stroke his head, and he's really gentle with him," the insider says. "You can already tell he's going to be the protective older brother!"

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As William and Kate adjust to living at Kensington Palace with their family of five, they’re both intent on being hands-on parents. "Kate does the night feedings, of course," the insider says, "but they take turns changing diapers. And they both try to bathe the baby together when they can."

The little prince soaks up all the attention, happily cuddled up next to the teddy bear from Peter Jones department store that Charlotte gifted him. Big brother George picked out a perfect musical mobile that hangs above the crib.

While many say the royals are content with the trio of tots they have now, there is some talk that they might not be entirely out of the baby-making business just yet. "William and Kate would love to have another baby," the insider reveals. "Not immediately, but they're a family-oriented couple and they think that four is an ideal number of kids — two boys and two girls!"

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