That on-off thing between KATY PERRY and JOHN MAYER is reportedly OFF again.  A source says, quote, "John just can’t commit, and he kept luring Katy back with promises that [he] was going to change, but then he didn't.

 

 

--"Katy was pretty crazy about him, so she kept giving him another chance . . . Finally she was like 'lose my number.'"