be the death of somebody

be the death of (one)

To be a source of intense aggravation. You'll be the death of me! Please call if you're going to be home late, so I don't worry.
See also: death, of

be the ˈdeath of somebody

(often humorous) cause somebody a lot of harm or worry: You children are so badly behaved! You’ll be the death of me one day!
See also: death, of, somebody