It seems that Princess Mia Thermopolis is all grown-up and ready to walk down the aisle. The beloved young adult fictional princess is ready to take on more mature issues and life changes in the latest installment of "The Princess," reports Entertainment Weekly.

The eleventh book in the popular young adult series is now on its fifteenth year, and what better way to celebrate Princess Mia's blunders as she makes her way to Genovia's throne than with a new book. According to the author of the "Princess Diaries" series, however, Book 11 is not aimed at teens of today but more for the teens 15 years ago, who grew up and matured with Princess Mia.

"Well, she is an adult. She's 26 in the book, so I think it would be odd to have it targeted to young adults. She's a woman now who's getting married and has some complex adult problems. It doesn't have huge amounts of sex but there are sexual references, so it might be inappropriate for 12-year-olds," Cabot revealed in an interview with Cosmopolitan magazine.

Cabot also revealed that she has no intention of prolonging the book series - the last installment went public almost six years ago. However, the clamor for now-adult fans of Mia's sarcastic and witty thoughts was difficult to ignore especially after the real-life royal wedding of Prince William and Kate Middleton.

"When I started the series, I really only intended it to go until she graduated from high school, and I had no ideas after that. And then I kept hearing from readers who were like, "Keep it going!" Then a big thing that happened was that Prince William and Kate Middleton got married, and readers were like, "When are we gonna get to hear about Princess Mia's wedding?" I started thinking, "You know, that isn't actually a bad idea." But you can't just have a story about a royal wedding - there has to be some tension and some other stuff going on," the author said.

When asked about what kind of "mature" exploits will Mia and her long-time boyfriend and now fiancé Michael Moscovitz will have in the upcoming book, Cabot quickly said that it will not be in line with "Fifty Shades of Grey." However, Cabot mentioned that fans have been vocal about Princess Mia and Michael having sex in a very royal fashion.

"Sex in the throne room was one thing that [the fans] immediately threw out there," the author said. "They heard it was an adult book and that was the first thing I heard. I'm not saying it doesn't happen. There's definitely sex in some weird places. I'm not sure that it's right there on the throne, because I'm pretty sure some people would walk in. You gotta be practical."

However, Cabot's teenaged readers need not to worry. The author recently released "From the Notebooks of a Middle School Princess," a book told from the perspective of Mia's newly-discovered half-sister Olivia Grace.

"Princess Diaries, Royal Wedding" is set to hit bookstores on June 2.