Take Paris Hilton and Nicole Ritchie. Friends since childhood, the pair did everything together including star in the most obnoxious reality show on television, The Simple Life. For those unfamiliar, The Simple Life was a sort of Ritchie Rich meets Survivor meets Dumb and Dumber as each series saw Hilton and Ritchie taken out of their comfort zones and placed in a radically different and challenging situation. Like a kitchen.

But in April the world got a whiff of a tiff between the pair and Mademoiselle Hilton released the following shock statement: "It's no big secret that Nicole and I are no longer friends. I will not go into the details of what happened. All I will say is that Nicole knows what she did, and that's all I am ever going to say about it." So what did Ritchie do that was so bad? Rumour has it that she was caught playing the "One Night in Paris" sex videotape at a party.

When Hilton released the aforementioned statement, Ritchie hit back with, well, pretty much nothing. Possibly because she was too busy trying to get someone to fix the pause button on her video remote control. Or maybe she was just proof-reading her tell-all blockbuster novel. That's right, folks. This month Ritchie hit back by releasing The Truth About Diamonds - a blatantly autobiographical novel lifting the lid on second-generation Hollywood celebs.

The story revolves around a young girl from a poor family who is adopted by a famous rock star at the age of seven, becomes part of Hollywood's A-List, develops a drug habit and goes into rehab. By complete coincidence Ritchie was the daughter of struggling musicians when she was adopted at the age of seven by rocker Lionel Ritchie. She became part of Hollywood's elite, developed a drug habit and went into rehab in 2002. But who cares about that? The really fun bit is the fact the villain of the novel is Simone Westlake - a two-timing, back-stabbing blonde model/actress with fake boobs who goes everywhere with her chihuahua, makes sex tapes and accidentally "loses" her mobile phone which is full of dozens of celebrity mobile phone numbers.

Sound like anyone we know? But Hilton and Ritchie aren't the only friends to have fallen out this year.

When model Kate Moss was caught allegedly snorting cocaine, British tabloids reported that her friend, British actress Anna Friel, immediately dumped her. Friel, a popular soapie actress who once dated singer Robbie Williams, was part of Moss's party crowd. However, the controversy surrounding the coke snorting Moss has led Friel to publicly distance herself claiming she "grew apart" from the model during her year abroad in the US.

"When I moved to New York for a year my priorities and responsibilities changed," Friel is quoted as saying. "When I came back from New York, things were different and the tabloids were full of stories about drinks, drugs and partying. I love my job so much. I don't want to ruin it by having a reputation."

But there's hope yet for Hilton, Ritchie, Friel and Skeletor. Just look at Nicholas Cage and Sean Penn. The actors who once co-starred in films like Fast Times at Ridgemont High were great pals until Penn started slagging off Cage in public, ridiculing his film choices and insinuating the actor had sold out. "Nic Cage is no longer an actor, he's more like a performer," declared Penn in 1999, probably after having watched Peggy Sue Got Married. Or Con Air. Or Face Off.

However, last month Cage announced he had buried the hatchet and no longer held any resentment towards Penn. "That was his opinion and, you know, we've since left it all behind us. But I think at any time an actor does something unusual it's going to be met with a certain amount of criticism. I've actively searched for that."