Heroes stars Hayden Panettiere and Milo Ventimiglia have ended their year-and-a-half long relationship, friends tell Life & Style.

A source close to the couple says they broke up because they were on different pages in terms of their lifestyle, "she's into the Hollywood scene and he's a business man. They work together still professionally but they're no longer a couple."

Hayden was spotted partying sans Milo on Feb. 13 and having a blast with girlfriends at Paris Hilton's 28th-birthday bash at Paris' LA home.

"Hayden is such a sweetheart," the friend says about the starlet. "She's single and ready to mingle."

Another friend reveals to Life & Style that Hayden changed her Facebook status to "Single" and noted she had "an amazing Valentine's weekend with the girls."

Paris' birthday party wasn't the first time in recent months that Hayden, 19, and Milo, 31, were spotted partying separately.

Hayden was partying with friends on Dec. 9 at West Hollywood's Apple Lounge. "She was having fun with her girlfriends, getting down with them on the dancefloor," an eyewitness told Life & Style. On Jan. 18, Hayden attended the Declare Yourself Rebirth of Citizenship Inauguration Kickoff in Washington, D.C. When Life & Style asked her how things were with Milo, Hayden smiled and walked away. And on Jan. 31, at the NBC Superfront Pre-Super Bowl party in Florida, she hung out with former Saturday Night Live funnyman Jimmy Fallon and Rainn Wilson of The Office, sans Milo.

Meanwhile, Milo was out until 3 a.m. in NYC on Feb. 7 with a group of guy friends at the SNL afterparty at Wildwood Barbeque restaurant.

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