Ashlee Simpson and Evan Ross

Ashlee Simpson and Evan Ross

Ashlee Simpson brought her fiancé to her ex-boyfriend's birthday bash.

The 29-year-old star, who got engaged to actor Evan Ross earlier this year, helped Ryan Cabrera celebrate his 32nd birthday at the Kia Motors Malibu Estate in California on Sunday (13.07.14).

An eyewitness, who saw the couple there, told "They were both super cute with one another, very affectionate and very touchy feely.

"At one point Ashlee even had Evan sitting on her lap as they conversed with their friends."

The blonde beauty dated Ryan, who was previously managed by her father, Joe Simpson, in 2004.

The 'Pieces of Me' hitmaker was also overheard "urging Ryan to play his new record for Evan so he could listen to it and maybe give him some insight on some lyrics that Ryan was struggling with. Evan and Ryan talked about collaborating and getting in the studio together. Both of them sounded super stoked on the idea and will be making it happen sooner than later."

Ashlee, who has five-year-old son Bronx with ex-husband Pete Wentz, will reportedly marry Evan, 25, at his mother Diana Ross' mansion in Los Angeles next month.