Patrick Dempsey's split from Jillian Fink was ''a long time coming.''

The 'Grey's Anatomy' star's wife, who has daughter, Tallulah Fyfe, 12, and seven-year-old twin sons, Sullivan Patrick and Darby Galen with the actor, recently filed for divorce after 15 years of marriage, but they were reportedly ''living separate lives for years.''

A source told PEOPLE magazine: ''It's been a long time coming. They have lived separate lives for years. They are involved in the children's lives separately. Patrick and Jillian have had disagreements for a long time. Emotionally, for Jillian, something was missing.''

The couple, who married in 1999, ''could not have been more opposite,'' according to another source.

Despite their issues, the 49-year-old actor, who was married to his manager Rocky Parker for seven years from 1987 to 1994, never wanted to get a divorce.

The source close to the family said: ''He was married and divorced before, and he has said he never wanted a divorce again because of his kids.''

Patrick previously credited Jillian for helping him to stay grounded.

He said: ''The best part about being married is feeling centered. Nothing else matters so much as long as you can come home and be with your family.''