It wasn’t in the cards for “Mad Men” star Jon Hamm and actress Jennifer Westfeldt. After nearly 20 years of dating, the longtime couple called it quits.

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

Arguments might have caused their breakup. "They've been fighting for a while, but now they're done,” an insider close to Westfeldt told Us Weekly. “They decided to finally split. It's sad."

Hamm, 44, did a 30-day rehab for drug and alcohol addiction in March. The treatment coincided with the Season 7 premiere of “Mad Men.” “Life throws a lot at you sometimes and you have to deal with it as much as you can," he told TV Week at the time. "That’s why you have family and friends and co-workers to help you with that."

Westfeldt supported him throughout rehab, ABC News added, but Hamm did not elaborate on their split. "I understand it constitutes news these days, but it’s between me and my family and not something for public consumption,” he said.

Hamm and Westfeldt battled cheating rumors for months. The actor’s rep denied Westfeldt had an affair while he sought therapy.

"The story that appeared in this week's edition of In Touch magazine is not true," the star’s rep told Us Weekly at the time. "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." 

Hamm and Westfeldt, who started to date in 1997, chose not to marry. They do not have any children.

The last time they were seen together in public was when they went to the after-party for the premiere of Netflix's “Wet Hot American Summer: First Day of Camp ” in New York July 22. They posed for a photo, all smiles.

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