The 75-year-old star and the 36-year-old actress have gone their separate ways after four years together following a series of rows, reported the Washington Post.
"They are so close but it wasn't meant to be. They're both dedicated to their craft so sustaining a relationship was always going to be tough," a source said.
The superstar has never been married, but hinted in March that he was willing to tie the knot with Lucila, despite there being a 39-year age gap between the pair.
"I never say never. It's possible," the source added.