By Stephen M. Silverman
Updated July 01, 2003 03:59 PM

More alleged trouble in Camelot is coming to light, thanks to “The Kennedy Curse,” a new book by Edward Klein that claims that John Kennedy Jr. and his wife, the former Carolyn Bessette, suffered marital problems that included disputes over drug use and fears of mutual infidelity.

Kennedy, 38, Carolyn, 33, and her sister, Lauren Bessette, 34, were killed on July 16, 1999, when the single-engine plane he was piloting crashed in the ocean near Martha’s Vineyard.

Carolyn and Lauren’s mother, Ann M. Freeman, did not immediately return the Associated Press’s call for comment Monday.

Klein’s book, a portion of which appears in the August issue of Vanity Fair magazine (and picked up by the Associated Press), says that John and Carolyn were already living separately at the time of the fatal accident.

Klein asserts – mostly citing information from unnamed friends of the couple – that the magazine publisher son of the late President and Jacqueline Kennedy and his wife, who had married in 1996, also argued over whether or not to start a family, on drug use, on Kennedy’s social life and on their downtown Manhattan apartment.

In 1999, Klein writes, the couple sought marriage counseling that lasted only four months – or, he says, until Carolyn stormed out of the therapist’s office when the topic of her alleged drug use arose.

She began sleeping in a spare room in the couple’s TriBeCa apartment, while Kennedy, “on the verge of calling it quits,” took up residence in the Stanhope Hotel on upper Fifth Avenue (near his late mother’s apartment).

Two days before they were killed, Klein writes, John and Carolyn got together for lunch at the Stanhope. With them was Lauren Bessette, who purportedly persuaded them to fly together to the wedding of Kennedy’s cousin, Rory Kennedy, in Massachusetts. Lauren, according to Klein, said she would accompany them as far as Martha’s Vineyard.

Klein’s previous books include “All Too Human: The Love Story of Jack and Jackie Kennedy” and “Just Jackie: Her Private Years.”