get cold feet

cold feet (a wave of timidity or fearfulness) — волна страха; внезапный приступ робости, страха или паники

get/have cold feet (be/become unable or afraid to do something important or dangerous; to lose one’s courage at the last moment. || cancel a plan, renege, back out) — оробеть; струсить, испугаться в последний момент; струхнуть; смалодушничать; || ~ отыграть назад, переиграть (из малодушия, страха)

Example 1: Just when I was about to ask the boss for a raise, I got cold feet. — Когда я уже был готов попросить его о прибавке, у меня вдруг не хватило смелости это сделать.

Example 2: I wanted to come to the party with you, but I got cold feet and changed my mind.

Example 3: "Did you go out with Jill over the weekend? Did you ask her?" "I wanted to phone her but I got cold feet at the last minute so I didn't."

Example 4: Suddenly I had cold feet and couldn’t sing a note. — Меня вдруг охватил страх, и я не мог выдавить ни одной ноты.

Example 5: They'll be married next week; that is, if Kevin doesn't get cold feet. —... ну, если, конечно, Кевин в последний момент не смалодушничает и не переиграет все.

Example 6: I usually get cold feet when I have to speak in public. (NTC's)

see also
[chicken out]
[turn to jelly]
[throw in the towel]
[show the white feather]
[наложить в штаны]
[yellow-bellied]
fraidy cat

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People normally have cold feet just before they get married. They are afraid and don’t want the ceremony to continue. It’s a momentary panic at the thought of living their entire life with one person. :))