let something slip through your fingers
let (someone or something) slip through (one's) fingers
1. To fail to catch, capture, or maintain custody of someone, usually due to their cunning or trickery. The officers very nearly apprehended the suspect, but let him slip through their fingers at the last second. We had the cell guarded by three people, but still we let her slip through our fingers somehow.
2. To fail to achieve something or make use of an opportunity. I had a chance to be a part of a Broadway musical once, but I was too unsure of myself and let it slip through my fingers. We've been training too hard to let another championship title slip through our fingers again this year!
let something slip through your fingers (or grasp)1 lose hold or possession of something. 2 miss the opportunity of gaining something.
2 1925 W. Somerset Maugham Of Human Bondage He was mad to have let such an adventure slip through his fingers.