"It's not a break," says a source close to the couple. "It's done."
By all accounts, the split is amicable. (Reps did not immediately respond for comment.)
"They're just in two different places in their lives – he's in college and she's focused on her music and career," says the source.
The "Wrecking Ball" singer, 22, has been busy recording in the studio, traveling with friends and attending events solo without Schwarzenegger, 21, who was spotted with pals at Coachella two weekends in a row.
In March, the USC student was photographed seemingly getting close to another girl while on spring break in Mexico, and another source close to the couple told PEOPLE at the time the duo was trying to work through the rough patch.
Indeed, it appeared the couple was soon back in sync. The two were spotted grabbing juice at Hugo's restaurant in Studio City and on March 23, enjoying a dinner date at Kiwami Sushi in Los Angeles.
Reporting by ELIZABETH LEONARD