Hayden PanettiereHeroes stars Hayden Panettiere and Milo Ventimiglia have reportedly ended their year-long romance.

The couple’s relationship was long an open-secret on the set of the superhero drama because then-18 Hayden is 12 years younger than Milo.

A source told Us Weekly that the age gap was ultimately in part to blame for the split: “Hayden is young. She likes to go out in the Hollywood scene and that’s not his style. Milo has been concentrating on work on his production company.

“It was a lifestyle conflict. They were in very different places.”

But the inside source added: “They are still on friendly terms. There are no hard feelings.”