Breakup alert! Heroes fans are not going to be happy about this one. Hayden Panettiere and Milo Ventimiglia have ended their relationship, according to Us Weekly. "It was a lifestyle conflict," a source tells the mag. "They were in very different places. They are still on friendly terms. There are no hard feelings." We hope not -- that would make things really awkward on set. The source also adds that Hayden "is young. She likes to go out in the Hollywood scene and that's not his style." Maybe Hayden needs a guy closer to her own age -- Milo is 12 years older than her! Who do you think Hayden would be cute with?