You could call it "digesting sour grapes", perhaps.

I like that.

While Aesop's sour grapes were a hot-headed passionate thing, this is something that develops slowly. Classical sour grapes are a hypocritical rationalisation, and a fox who suddenly realised how it could get the grapes after all would jump at the chance. But with digested sour grapes, the lack of desire is a permanent part of oneself.

Some of the other replies to my comment seem to be trying to convince me that I do really want the grapes deep down. Aesop's fox does, and there was probably a time that I did too. But now I don't.