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Zac Efron and Lily Collins' spring fling is over.

After just three months together, the "Lucky One" actor, 24, and the "Mirror Mirror" actress, 23, have split, multiple insiders tell Us Weekly exclusively.

"They're no longer together. They were never serious, though; it was just a casual thing and it fizzled," one insider explains. "They were never in the same place at the same time."

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A second source adds, "Zac was never very serious about her. He didn't talk about her to friends."

The stars were first spotted holding hands during a friend's birthday dinner at Los Angeles eatery STK on Feb. 8. After that, the low-key stars, who have been photographed together only once, only grew further apart.

VIDEO: Lily Collins holds hands with Zac Efron

"It's true that their schedules are crazy right now, which isn't conducive to a relationship being easy," a pal tells Us.

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Prior to his relationship with Collins, Efron was in a long-term relationship with his "High School Musical" co-star Vanessa Hudgens, 23. Collins and her "Abduction" co-star Taylor Lautner, 20, ended their courtship in September 2011.


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