Another source confirmed the news to PEOPLE, indicating that the former couple have broken up before in the past and "have had trouble getting along for several years."
"Friends were shocked. Helen and Matthew always appeared to be super in love," another insider told In Touch. "Their married friends would joke that they were jealous of their relationship."
The breakup comes two years after Hunt announced that she and Carnahan were developing a TV series together, but she hasn’t spoken of the project since.