Credit: Flynet Pictures

Nothing can keep them apart!

Blake Lively flew thousands and thousands of miles to be with Leonardo DiCaprio -- traveling across the world from the U.S. to Australia for a belated birthday weekend, a source confirms to Us Weekly.

Lively, who turned 24 last Thursday, visited her man, 36, who's currently shooting The Great Gatsby in Sydney.

The twosome (whose romance began in late spring with a whirlwind tour of Europe's poshest hotspots) were reportedly spotted having a romantic dinner Saturday night at Sydney hotspot Aria -- with a prime view overlooking Sydney's famed harbor.

But, indeed, it was a short and sweet trip. A source close to the Gossip Girl actress confirms that she's already back in the States as of Tuesday.