Jeffrey Dean Morgan and Mary Louise Parker at the Premiere of 'P.S. I Love You' at the Grauman's Chinese Theater. Los Angeles, California - 09.12.07

The couple - who both appear on the hit U.S. TV series - got engaged in February this year (08) after they began dating in 2006. They briefly split in June (07), but later reconciled their relationship.

The pair's split has been blamed on their "differing lifestyles", reports the Associated Press, but Parker hopes to remain friends with Morgan.

Source: WENN