AceShowbiz -

Having been friends with Jon Hamm and Jennifer Westfeldt, "Mad Men" creator Matthew Weiner claimed the former couple has been dealing with "tough times" after announcing their separation last week. "It's a tough time for [both of them]," Weiner told Us Weekly at the 2015 Creative Arts Emmys held at the Microsoft Theater in Los Angeles on Saturday, Sept. 12.

"I know both of them very well. They are both really gifted artists and it's rough," Matthew added. "But it's also - it was a very long relationship."

Meanwhile, an insider told Us Weekly that Jon and Jennifer "definitely tried" to work on their romance, but their different views on family has forced them to call it quits after 18 years together. "There's always been a rift," said another source close to the actress. "Because he wanted kids and she didn't."

Jon, 44, and Jennifer, 45, announced in a joint statement to PEOPLE earlier last week that they "decided to separate ....." but "will continue to be supportive of each other in every way possible moving forward." It was claimed shortly thereafter that writer/director Jennifer got tired of Jon's "party-heavy lifestyle."