Jon Hamm and Jennifer Westfeldt Jon Hamm and Jennifer Westfeldt

Mad Men star Jon Hamm is splitting from longtime girlfriend Jennifer Westfeldt, according to People.

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

The duo has been the subject of breakup rumors for several months, although they publicly denied it in April, shortly after Hamm completed a rehab stint for alcohol abuse. Hamm credited Westfeldt for her help in overcoming his addiction.
See other celeb couples that have called it quits

Westfeldt has been a red carpet mainstay by Hamm's side throughout Mad Men's celebrated seven-season run. Hamm is scheduled to appear at the Emmys later this month, where he is once again nominated for Lead Actor in a Drama.

Hamm and Westfeldt began dating in 1997 and have co-starred together in Westfeldt's films Kissing Jessica Stein and Friends with Kids.

VIDEO: Jon Hamm checks out of rehab for alcohol addiction

-shockwave-flash' height='338' width='600'>