Celebrity news websites claim the couple have called time on their relationship after dating for less than two years.
The break-up reports come just a week after Zellweger sat in the audience next to Cooper’s mother as he was interviewed on US television.
Cooper proudly pointed his girlfriend out as he chatted to host James Lipton during an episode of Inside The Actor’s Studio, which aired last week.
The Bridget Jones star blushed before standing up to wave hello to the other audience members.
Cooper, 36, and Zellweger, 41, met six years ago on the set of big screen thriller Case 39, but romance did not blossom until summer 2009.
The couple have remained tight-lipped about their relationship but now, according to reports, have gone their separate ways. Their reps have refused to comment on the reports.
Zellweger was previously married to singer Kenny Chesney – for just four months. Cooper also had a short marriage to actress Jennifer Esposito.