Heroes co-stars Hayden Panettiere and Milo Ventimiglia have split after a year-long romance. The two stars are still on friendly terms, according to pals, but their lives were going in different directions.

A source tells Usmagazine.com, "It was a lifestyle conflict... (She) is young. She likes to go out in the Hollywood scene and that's not his style. (Ventimiglia) has been concentrating on work, on his production company."

At 31, Ventimiglia is 12 years older than the teenage actress. The pair reportedly spit last week.

(This news article provided by World Entertainment News Network)