A: Why is John insisting on breaking up with Cathy?

B: Her remarks about his inability to earn a decent living cut him to the quick.

A: Well, that kind of talk really hurts.

Note: This idiom means “to be deeply wounded, to have one’s feelings hurt.” The noun “quick” means the living, as well as the most vital and important part. Today it also means the very sensitive flesh between the fingernails and skin. To be “touched to the quick,” meaning to be deeply affected, has been used since the 16th century. Another version is “stung to the quick” for “wounded, distressed.”