To a fault
Definition 1 of 1
Pro Tip 1/3Negative Implication
Indicates an excessive trait that can lead to negative outcomes or perceptions. 
His attention to detail is meticulous to a fault, causing projects to fall behind.
Pro Tip 2/3Emotional Nuance
Often used to show a mix of admiration and concern about someone's extreme behavior or characteristic. 
He's caring to a fault, and sometimes people take advantage of his kindness.
Pro Tip 3/3Subtle Warning
May serve as a polite warning or a gentle criticism about someone's behavior. 
You are trusting to a fault; just be careful not everyone has good intentions.