Longtime couple Jon Hamm and Jennifer Westfeldt have split up, according to the actor's publicist.

Hamm, 44 and best known for his lead role in "Mad Men," and Westfeldt, 45, of "Kissing Jessica Stein," announced their break-up in a statement yesterday.

People.com first reported the story.

"With great sadness, we have decided to separate, after 18 years of love and shared history," the couple said in a statement. "We will continue to be supportive of each other in every way possible moving forward."

They were last seen together cuddling at a party following the premiere of Netflix's "Wet Hot American Summer: First Day of Camp," according to the New York Post.

Hamm was treated for alcohol abuse earlier this year.

The couple acted together in the film "Friends with Kids," which Westfeldt wrote and directed.