Their hectic schedules led to the break up, according to Usmagazine.com. A source says, "They're no longer together. They were never serious, though; it was just a casual thing and it fizzled (out). They were never in the same place at the same time."
Lily Collins, daughter of popstar Phil Collins, was previously linked to "Twilight" star Taylor Lautner. Efron had a longterm relationship with "High School Musical" co-star Vanessa Hudgens.