I'm not sure that I know the underlying psychology there, but this sounds painfully similar to things that my own DD11 began saying about three years ago when she entered middle school. It truly doesn't seem to be "perfectionism" though it can sure look like it. DD's standards seem to be pretty idiosyncratic and variable, and it is the kind of thing that she says about not just academic work-- but ANYTHING that isn't going well (by her standards). It doesn't seem to respond to anything external, but my gut says that it is rooted in her self-perceptions and in her burgeoning recognition of how her asynchrony impacts her ability to acheive the way she would like.
To me this sounds exactly like perfectionism. How do you see it as different?