The 47-year-old beauty has been married to Moder since 2002 but he is said to have "had enough" of the star, reported OK! magazine.
"Danny just doesn't feel like they have a true partnership. (It's always) been (Julia's) way or the highway. (She is) very emotional (and can go from) screaming one minute and then apologising the next. (She) goes off on rant after rant, pointing the finger at Danny at ever opportunity. (He's) had enough!," a source said.
And Roberts has had a tough two years after losing her half-sister Nancy and mother Betty.