Kim Kardashian, Lady Gaga, Salma Hayek, Kate Beckinsale... you name them and they showed up to celebrate Leonardo DiCaprio's 49th birthday on November 11.
However, sources tell Woman's Day there was one noticeable absence that had tongues wagging throughout the night – Kate Winslet.
Since starring in 1997's Titanic, the pair have worked hard to downplay romance rumours, but the one thing they always agreed on was the fact that their friendship was watertight.
Despite their incredibly close bond, which has seen the co-stars' team up again over the years, sources confirm that these days the duo's relationship is sinking faster than the Titanic.
"Kate wouldn't step foot in his house, not when there's a big party going on.
It's nothing personal – she just avoids the wild side of Hollywood parties and likes to keep things with Leo professional," confides one sleuth. While Kate would rather avoid the shining lights of Tinseltown, sources say there's more to it that just not loving a party and that relations between the pair are seriously strained.
"They struggle to find things in common any more and everyone suspects there's been a falling out over Leo's transient love-life," tells the insider.
Despite now being in a seemingly committed relationship with 25-year-old model Vittoria Ceretti, Leo's penchant for young women is said to have left Kate questioning some of the decisions her friend has made.
"Understandably, Kate's sick of trying to get to know his latest girlfriend, only for a new one to be in place the next time. She quite literally can't keep up and doesn't like that he's unable to commit," tells the insider.
"All these ladies seem sweet, including Vittoria, but none seem quite right. Kate worries about his inability to connect to someone on a deeper level."
Despite being a year younger than Leo at 48, insiders say Kate has constant anxiety about being seen as a "nagging mum" to Leo and doesn't want to further flame their fallout.
"He's my friend, my close friend. We're bonded for life," she once confessed of their relationship.
After suffering two divorces, those close to the English actress say she is committed to her current marriage, to businessman Edward Abel Smith and raising her three children.
"She'd rather have fun with her kids than attend Leo's birthdays with a bunch of show-offs strutting about looking for someone to help them with their career," quips the source.