Reflecting on his own past when he said he was "insecure" about himself and how no one is always their best, he explained, "I think that’s probably what happened to Katie is she had a couple of bad moments and that’s what everybody wants to – that’s her label right now and that’s not really fair I don’t think."
Duhamel also named "Life as We Know It" as his favorite romantic comedy that he’s starred in.
Katherine Heigl and Josh Duhamel starred in "Life As We Know It" in 2010. (Getty)
"It was not just a comedy … It had real sort of drama based on this tragedy that happens at the opening of the movie," he said of the movie about two godparents (Duhamel and Heigl) who fall in love while raising the children of their friends after their deaths.
The two also starred in 2011's "New Year's Eve" together.
In 2008, Heigl withdrew her name from Emmy consideration, saying that she hadn’t been given material on drama "Grey’s Anatomy" that would "warrant" an award. She later apologized to creator Shonda Rhimes and the writers.
Josh Duhamel said he thought Katherine Heigl was "great" when he worked with her. (Ryan Miller/Getty Images)
She also complained about 17-hour "cruel, mean" days on the set of the hospital drama during an appearance on David Letterman. She left the show in 2010.
In 2014, Heigl defended herself to Meredith Viera, saying, "I’m not a rude person. I’m not an unkind or mean person. I would never go out of my way or consciously try to hurt anyone’s feelings or make them feel bad or not be professional and do my job. I like my job. But I will continue to stand up for myself."
She added in the years since she left "Grey's Anatony" she had learned to be more thoughtful about when and how she speaks out about concerns.