03/20/2009 05:12 am ET | Updated May 25, 2011

Hayden Panettiere And Milo Ventimiglia Split Up

Heroes costars Hayden Panettiere and Milo Ventimiglia have called it quits, Usmagazine.com has learned.

"It was a lifestyle conflict," a source close to the couple tells Us, adding that the split happened within the last week. "They were in very different places."

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