Katy Perry and John Mayer did what many of us couldn't do ... show up at the same concert after apparently breaking up ... each with a date.

Katy and Orlando Bloom seemed stoked to be among the relative few who got to enjoy the Adele concert at the Wiltern in L.A.  

John arrived with a new girl, whose musical taste is clearly varied ... check out the Tupac shirt.

They weren't seated near each other, so if there is a blow, it's softened.