The PIRATES OF THE CARIBBEAN star and Dornan, who recently landed his first movie role in forthcoming film MARIE ANTOINETTE, first met in August 2003.
An insider tells British newspaper the Daily Mirror, "Keira's gutted. She really thought what she and Jamie had was love but it just wasn't meant to be.
"They both wanted it to work but in the end it was just untenable. They were having crisis talks on an almost daily basis so the decision was reached to finally call it a day."