Ruth Negga and Dominic Cooper first met in 2009 when they worked on a play for the National Theatre in London

Ruth Negga and Dominic Cooper have parted ways.

The former couple, who costarred in AMC’s Preacher, have ended their relationship after eight years together, a source confirms to PEOPLE. Page Six first reported the news, with a source telling the outlet that “their romance ran its course” and Negga, 36, and Cooper, 39, “remain friends.”

Get push notifications with news, features and more.

The pair, who were last photographed together in December 2017, first met in 2009 when they were working on the play Phèdre for the National Theatre in London.

Image zoom

Dominic Cooper and Ruth Negga in December 2017

Since then, Negga and Cooper collaborated on several projects including the 2016 film Warcraft. In addition, they both garnered roles in the Marvel Universe: she made a cameo on Agents of S.H.I.E.L.D. while he starred in Captain America: The First Avenger and Agent Carter.

Want to keep up on the latest from PEOPLE? Sign up for our daily newsletter to get our best stories of the day delivered straight to your inbox.

Image zoom

The Oscar-nominated actress previously talked about her relationship in July 2017. Detailing their bond on the set of Preacher, she told The Edit, “It would be so lonely if he wasn’t there. People say, ‘Never go out with an actor.’ But if you were with someone with a normal job, and one of you had to go away, how would that work?”

Cooper’s film, Mamma Mia! Here We Go Again, starring ex Amanda Seyfried, will hit theaters on July 20.