U.S. actress Amanda Seyfried and her British boyfriend, actor Dominic Cooper, have broken up, a source told People.com.

Seyfried, 24, and Cooper, 31, co-starred in the 2008 blockbuster movie musical "Mamma Mia!"

"Amanda and Dominic have been on and off for a while -- and right now they're taking a break," an insider told People.com.

"But they're great friends and could still get back together."