Harmon, star of the TNT cop drama Rizzoli & Isles, got engaged to Sehorn, who currently works as a college football analyst for ESPNU, back in 1998. Sehorn popped the question by surprising Harmon during a taping of The Tonight Show with Jay Leno and asking her in front of the audience.
Harmon's TNT drama shoots in Los Angeles while her family lives in Charlotte, North Carolina. The 42-year-old actress has spoken in the past about the difficulties of maintaining a long-distance marriage, saying, "You have to be really considerate of each other, really kind to each other... It's a lot of work."
Harmon and Sehorn, 43, have three daughters together: 5-year-old Emery, 9-year-old Avery and 11-year-old Finley.
"For the sake of their children, they ask for respect and privacy as they navigate this time in their lives," Harmon's rep told People.
Harmon and Sehorn are among a number of celebs who have recently separated or filed for divorce. Last week, former talk show host Ricki Lake filed for divorce from her husband Christian Evans. Check out the video below for more on that story.