be the death of somebody

be the death of (one)

To be a source of extreme worry, distress, aggravation, or other effects too intense for one to endure. 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