sour grapes an attitude in which someone disparages or pretends to despise something because they cannot have it themselves.
☞ In Aesop's fable The Fox and the Grapes, the fox, unable to reach the tempting bunch of grapes, comforts himself with the thought that they were probably sour anyway.
2012Washington Post His comment, made on a conference call with donors, that President Obama won by offering 'gifts' to various constituencies reeked of sour grapes and a poor post-game analysis.