Jon Hamm and Jennifer Westfeldt have been together for a long time, but they finally threw in the towel 18 years down the line. Dating since 1997 when they met at a mutual friend's birthday party, the couple released a statement to announce the separation:

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

A source from Westfeldt shared with Us Weekly: "They've been fighting for a while, but now they're done. They decided to finally split. It's sad."

The couple defended their relationship in April when reports came out that they had separated before Hamm's recent rehab stay to fight alcohol addiction.

Westfeldt, who's is most recently attached to Mad Men, was rumored to have been seeing someone else, but her rep stated: "The story that appeared in this week's edition of In Touch magazine is not true. The only gentleman Jennifer visited regularly in Connecticut was Jon, while he was in rehab. They continue to ask for the public's understanding and sensitivity during this challenging time."

The pair was still attending public events together in January when they were seen on Broadway attending On the Town.

They posed with the cast after the show and all seemed well. Hamm, 44, and Westfeldt, 45, chose to continue dating throughout the years rather than marry and have children.

"I have a tremendous amount of respect for my friends who do balance this particular career with raising a kid, 'cause it's a tricky environment to bring them into... So not for us just yet," Hamm shared with the Hollywood Reporter in 2011.