Bad Behavior on "Heroes" Set

It's never a good thing when dating costars break up and it seems Hayden Panettiere and Milo Ventimiglia are no exception.

MonstersandCritics.com reports that Panettiere, 19, is trying to get the bosses of the hit show to get rid of Ventimiglia's character, Peter Petrelli. A friend told OK! magazine, "She refuses to be on the set at the same time as him. She is making it difficult for everyone involved."

A rep for Panettiere has denied this, saying that the split was an amicable one. But it's also been said that the root of the former couple's problems was the age difference. Ventimiglia is 31, making them 12 years apart.

It seems like Panettiere has some more growing up to do. Heroes fans hope that it doesn't affect the flailing show's attempt to get back on top this season.