On-and-off couple Katy Perry and John Mayer are off again ... for now.

A source told Us Weekly, "It's sad," but added, "it's not over until it's over. You have to see how things play out."

Apparently their schedules got in the way and the split was pretty amicable. Another source said, "She's leaving the window open. They have both been so focused on work."

The pair were relatively quiet about their relationship in the press, but did allude to their happiness with one another.

In a '60 Minutes' interview, Mayer revealed that his relationship with Perry was refreshingly normal. “For the first time in my life, I don’t feel like I’m in a celebrity relationship. I really don’t.”

“I know it’s high profile," he said, "[But] it doesn't feel that way for me. I’m saying that for me it feels like something that’s very human.”

The couple first got together in summer 2012, then split that August, only to reunite in September. They made their first public, confirmed appearance together in December 2012, likely to a bit less fanfare than they'd expected.

The move comes as a bit of a surprise, considering the couple had engagement rumors swirling around them this past Valentine's Day. We're gonna go ahead and blame this split on that ring.

C'mon, John. You're not a jerk anymore -- you can do better!