Will Arnett, Amy Poehler Reunite for Her 41st Birthday Party

Will Arnett and son Abel on September 16, 2012 in Los Angeles, California. NPG.com

When Us Weekly first broke the news earlier this month that Amy Poehler and Will Arnett were separating after nine years of marriage, a source told Us it was "very amicable."

Clearly, Arnett and Poehler are committed to keeping it that way. On Sunday, Arnett was spotted — along with his and Poehler's two sons, Archie, 3, and Abel, 2 — attending the Parks and Recreation star's 41st birthday party, E! News reports.

The couple and frequent costars (joint credits include Arrested Development, Blades of Glory, and Horton Hears a Who!), who wed in 2003, both received Emmy nominations this year: Poehler has been nominated for Outstanding Lead Actress in a Comedy Series and Outstanding Writing for a Comedy Series, while Arnett received a nod for his guest role as Devon Banks on NBC's 30 Rock.

Poehler spoke to Us earlier this year about how much she admires her husband.

"My children are perfect," she gushed. "And they've gotten all their good stuff from Will."

Despite their decision to part ways, an insider close to the pair says the comedians "have a lot of respect for each other" — and adds that "there's still love between them."

Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics and more delivered straight to your inbox!

Want stories like these delivered straight to your phone? Download the Us Weekly iPhone app now!