You hear that??
It's the sound of millions of females weeping around the world, because our favorite shirtless hottie is OFFICIALLY off the market!
If our sources are correct, Zac Efron has been getting hot and heavy with his Neighbors co-star Halston Sage for some time now—and he's apparently super happy!
While this breaks our hearts, hopes and dreams, we're totally on board with Zac finding a good lady!
An insider revealed the duo has gotten extremely close since his rehab stay and flick filming last spring: