Amy Poehler and Will Arnett are separating after nine years of marriage, his rep confirmed to Page Six last night. “SNL” alum Poehler and “Arrested Development” star Arnett have two sons — Archie, 3, and Abel, 2 — and have been living in New York. US Weekly reported the split is “very amicable.” The pair have appeared on TV together, with joint credits including “Blades of Glory.” Arnett also guest starred in an episode of Poehler’s NBC comedy “Parks and Recreation.”