HAYDEN PANETTIERE and MILO VENTIMIGLIA

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 (ends13Feb09).

Source: WENN