To be displeased with in a jealous way
Suppose a person is after something or somebody. For example, Tom wants to be with Jane, but somebody else wins her heart, and Tom says, “She was ugly/fat/... anyway.” Is there a word or idiom to describe Tom's reaction?
Solution 1:
There is an idiom, "sour grapes", meaning that you saying negative things about something because you couldn't get it. It's from the fox and the sour grapes story, by Aesop.
Merriam-Webster definition: "disparagement of something that has proven unattainable"