Book: JFK Jr.'s Troubled Marriage

John F. Kennedy Jr. and his wife, Carolyn, were having marital problems and were living apart when they died in an airplane crash in July 1999, a new book claims.

The August issue of Vanity Fair magazine contains excerpts from Edward Klein's new book, "The Kennedy Curse," which asserts Kennedy and his wife differed on whether to have a family, on drug use, on Kennedy's outgoing lifestyle and on their Manhattan apartment.

At times, each feared the other was being unfaithful, the excerpts say. Most of the information is attributed to unidentified friends of the couple.

Kennedy biographer Lawrence Leamer scoffs at Klein's claims.

"I don't recognize it," he told CBS News Early Show co-anchor Harry Smith Tuesday. "I have had all John's friends cooperating. This book has hairdressers and manicurists. These are not John's friends, all these anonymous sources."

Kennedy married Carolyn Bessette on Cumberland Island, Georgia, in 1996.

It had been reported earlier the couple had marital problems.

In 1999, Klein says, the couple began marriage counseling but after four months, Bessette Kennedy stormed out when the therapist mentioned her drug use. She began sleeping in a spare room of the apartment and Kennedy, "on the verge of calling it quits," moved into the Stanhope Hotel on Fifth Avenue.

"I spent most of the yesterday talking to John's close friends," said Leamer, who is writing his own book called "The Kennedy Sons." "They called me and said how disgusted they were.

"All these things aren't true," Leamer said. "The idea that John was disloyal to her sexually — this was one of the great themes of his life, that he wanted to be loyal. He wanted this marriage to work out. He didn't want to end up like some of his cousins."

Two days before they were killed, Klein says, they met for lunch at the Stanhope with Bessette Kennedy's sister, Lauren Bessette, who persuaded them to fly together to the wedding of Kennedy's cousin, Rory Kennedy, in Massachusetts. Lauren Bessette said she would go with them as far as Martha's Vineyard.

On July 16, 1999, Kennedy, 38, his wife, 33, and her sister, 34, were killed when the single-engine plane Kennedy was piloting crashed in the ocean near Martha's Vineyard.

Klein says when Kennedy graduated from flight school, he gave his instructors a photo of himself and inscribed it, in part, with, "People will only care where I got my training if I crash."

Klein is also the author of "All Too Human: The Love Story of Jack and Jackie Kennedy" and "Just Jackie: Her Private Years."

Leamer says the trashy revelations are a matter of money.

"It's about greed. It's about the greed of a publisher, about greed of a magazine," he told CBS News.