Hayden Panettiere and Milo Ventimiglia have broken up.

The Heroes stars have dated since last year.

A source close to the couple told Us magazine, “It was a lifestyle conflict. They were in very different places. They are still on friendly terms. There are no hard feelings.”

The source goes on to say the 12-year age gap probably contributed to the split. Panettiere is 19 and Ventimiglia is 31.

“[Hayden] is young. She likes to go out in the Hollywood scene and that’s not his style. He has been concentrating on work on his production company.”