Be the despair of somebody
Definition 1 of 1
Pro Tip 1/3Emotional Weight
The phrase carries a strong emotional charge, often implying deep disappointment or distress. 
Despite his talents, he's the despair of his mentors with his lack of ambition.
Pro Tip 2/3Negative Connotation
Using 'the despair of' indicates a negative sentiment towards someone's behavior or situation. 
She is the despair of her team, missing deadlines consistently.
Pro Tip 3/3Hyperbole Usage
It's often used hyperbolically to emphasize how challenging someone or something is. 
This complicated case is the despair of the detectives.