Matt LeBlanc thought Joey and Rachel's romance was too 'incestuous' when Friends writers first revealed plot

Matt LeBlanc had doubts about his character Joey Tribbiani's relationship with Rachel Green. Photo / Getty Images

It's the friendship turned romance that surprised us all.

And now the inside story of Friends characters Joey Tribbiani and Rachel Green's relationhsip has been revealed.

In a new book by Kelsey Miller she describes how Matt LeBlanc at first reacted with horror to the idea of Joey romancing Jennifer Aniston's Rachel, the Daily Mail reports.

"When [creators Marta] Kauffman and [David] Crane first approached the cast in Season Eight with the idea of Joey falling in love with Rachel, everyone balked," she writes in an excerpt on People magazine. "LeBlanc said it felt incestuous (especially uncomfortable after so many years of cultivating a brotherly bond with the female characters)."

At the end of season nine, while Rachel was pregnant with long-term love interest Ross Geller's baby, she began to get romantically involved with Joey.

At first Joey was more interested in Rachel, before she began crushing on him in return.

Ultimately the two did not end up together and Rachel got back with Ross, sacrificing her dreams of a career in Paris to be with him, despite her friends urging her to go.

In I'll Be There for You: The One About Friends, which was published Tuesday, Miller writes that Joey and Rachel were never fated to stay together.

"They would never have sex or say the L word; that would be too much to recover from."

The NBC series hasn't been on screens for 14 years, with the last episode airing in May 2004.

Aniston has said Friends could never happen now because of society's reliance on technology.

The 48-year-old insists scenes of the characters interacting in the Central Perk coffee shop wouldn't reflect modern life as people are too interested in their mobile devices to have proper conversations.

She said: "We were jokingly saying that if Friends was created today you would have a coffee shop full of people that were just staring into iPhones.

"There would be no actual episodes or conversations."

Friends also starred Matthew Perry [Chandler Bing], Courteney Cox [Monica Geller] and David Schwimmer [Ross Geller].