An exact match to what you are describing, but in two or more words is the expression
" ... cold feet ..." eg.
"Matthew got cold feet and didn't attend the blind date."
Examples at end.
Shy, tongue tied, wary, apprehensive, nervous, embarrassed, trepidatious ( :-) ) ,
from Stephen Crane's novel Maggie, a girl of the streets, 1896:
- "I knew this was the way it would be. They got cold feet."
Free dictionary :
- cold feet - timidity that prevents the continuation of a course of action; "I was going to tell him but I got cold feet"
- apprehension or doubt strong enough to prevent a planned course of action