According to author Christopher Andersen, John Kennedy Jr had a passionate relationship with pop idol Madonna, much to the dismay of his mother Jackie Onassis, who hated the popular singer because of her strong resemblance to Marilyn Monroe.

In his new book ‘The Good Son: JFK Jr. and the Mother He Loved,’ the author claims that JFK Jr, who was once dubbed the sexiest man alive, began seeing the Madonna in 1988, while she was still married to actor Sean Penn.

Quoting dancer Erika Belle, one of the pop star’s closest friends at the time, the book says that JFK Jr was completely head over heels for Madonna. “You could see it in his eyes that first time they met. John was totally in awe,” Ms. Belle said.

During their relationship, JFK Jr and Madonna would reportedly meet at a health club and would occasionally jog around Central Park together in the early morning.

According to the book, at some point during the affair JFK Jr decided to introduce the singer to his mother. The fact that Madonna’s use of crucifixes and other Catholic images had been deemed sacrilegious by the Vatican certainly didn’t benefit the relationship between the two women.

However, what is said to have upset Jackie most of all was seeing a copy of Life Magazine which featured Madonna on the cover dressed up as Marilyn Monroe. As the famous actress was one of several women who her husband had famously cheated on her with, this was certainly an unwelcome reminder of a horrible period in her life.

JFK Jr is known to have had relationships with many famous women including Sex and the City actor Sarah Jessica Parker, who he is said to have been dating at the same time as Madonna.

He died in 1999 in a plane crash along with his wife Carolyn Bessette, and her elder sister Lauren.