Ariana Grande is on billboards promoting this weekend’s “Grammys” . . . but she’s not even going to be there.  She just backed out of the show, and it IS personal.

Sources tell Variety that Ariana felt “insulted” after producers refused to let her perform “7 Rings”, the latest single from her album “Thank U, Next”, which comes out Friday . . . two days before the Grammys.

They eventually agreed to let her do it in a medley, but for whatever reason they wanted to choose the other songs.  They weren’t being so demanding with the other performers, so Ariana backed out.  She hasn’t commented.