Leonardo DiCaprio, and Bar Refaeli, are back on

Leonardo DiCaprio, 33, and Bar Refaeli, 22, are back on.

Leonardo and Bar were spotted holding hands at the Polo Lounge in Beverly Hills on Dec. 20.

"They were never really 'off,'" a DiCaprio source tells Us Weekly.

"It was always a distance thing," the source adds. "Leo was making a movie in Morocco [this year], and Bar had her modeling career."

Refaeli's mom, Zipi, tells Us: "Bar is working all over the world.

Says the DiCaprio pal, "It's a struggle to make a relationship like theirs work, but yes, they're together."