Cameron, a 20-year-old USC junior, will sit out the upcoming basketball season.
"It's an exciting time in their life," says a source who knows both athletes. "They both have support from their families."
Leinart, a Heisman trophy winner and close pal of Nick Lachey, was linked romantically to Paris Hilton in the past.
He is currently raising money to start the Matt Leinart Foundation, a learning center for underprivileged and disabled children. "Kids are important to Matt," his rep tells PEOPLE. "He really wants to help kids who can't help themselves."