Well, that was a quick engagement. Cameron Diaz and Benji Madden got engaged in December and the two are set to wed Monday night (Jan. 5), US Weekly reports. Details about the impending nuptials are being kept under wraps, but a source told the magazine that Madden and the "Annie" actress held a rehearsal dinner for family and friends in Beverly Hills Sunday night.

Guests were handed drinks as they arrived and dinner was served around 7:30 p.m. Reportedly, the event lasted around three hours. Madden and Diaz have been dating for almost eight months. The pair first stepped out as a couple in May after being introduced to each other by Nicole Richie, who's married to Madden's twin brother Joel.

"Everyone thinks it's wild, but are so happy for them," a source told US about the whirlwind romance. "Benji tends to fall in live easily, but this time it's for real and he landed a great girl. They obviously both make each other incredibly happy, and there's nothing better than that."

The source also said that Diaz's mother, Billie Early, is ecstatic about her daughter's new romance.  

"Billie has been gushing about Cameron's new relationship," the source said. "She absolutely loves Benji and she hopes this is the man her daughter will finally settle down with."

The 42-year-old actress recently dished about her relationship with the 35-year-old Good Charlotte rocker to Cosmopolitan magazine for their January issue.  

"Timing is everything," she said. "If you get into a relationship where you want something the guy doesn't want, it's never gonna work."

"No matter how old you, finding the guy who's in the same place as you are and wants to show up is the only way a relationship works, period," Diaz added.