(Richie has been married to Benji's brother, Joel Madden, since December 2010.
They're parents to daughter Harlow, 6, and son Sparrow, 4.) PHOTOS: Cameron's leggy looks Indeed, Diaz and Richie appear to be close friends.
Guests included Reese Witherspoon, Gwyneth Paltrow, and Samantha Ronson. "It was one of those things where everyone tells you, 'You just know when you know,'" she explained. "The first thing I said when I first met my [would be] husband was, 'He's hot,'" she confessed. We had never been in the same circle."The couple didn't formally meet until she hosted a dinner party at her house with Nicole and Joel. " The two hit it off and began dating, and the rest is history! You just know when you know.' Like you're my husband."Although she knew Benji's sister-in-law, Nicole Richie, and his brother, Joel Madden, for a couple of years, Cameron and Benji didn't really cross paths.Shortly after, Madden began dating socialite party-girl Paris Hilton, whose former best friend, Nicole Richie, married his brother Joel. The pair split a few days ago after more than nine months of dating, a source close to Hilton tells PEOPLE.