Failure to do something out of fear

I'm looking for a word that implies that one intended to do something but then didn't due to being afraid. Like someone who never asks out a person of interest because of the fears of rejection or loss of a friend. Hesitate is close, but to me it implies that the action will happen eventually, and I want the word to mean that the person never goes through with it because he or she is so afraid (its synonyms seem to have the same implications). Is there a word in English that means a complete failure to go through with something out of fear?

It is indeed a bit difficult to find a single word that fits the bill, but you might try:

to balk

~ to stop, as at an obstacle, and refuse to proceed or to do something specified (from Dictionary.com)

~ to stop short and refuse to go on (from the Free Dictionary)

~ to suddenly show that you do not want to do something : to refuse to do what someone else wants you to do (from Merriam-Webster online)

However, if you want to ensure that the concept of "because of fear" is included, then you may want to opt for one of the following multi-word expressions:

to chicken out

to cop out

to wimp out

to get cold feet

These all have the same meaning that The Free Dictionary gives for "chicken out:"

~ to fail to do something through fear or lack of conviction

1. Ahmed was paralyzed by fear.
2. The prospect of talking to her professor haunted Janice.
3. Cowed and defeated, the soldiers returned to their bunker.
4. Trembling, ashamed, broken, and brokenhearted, Peter retreated to the safety of his books.
5. Pacing, sitting, standing, fretting, cursing the rain: he could find no solace for his ambivalence and no justification for his cowardice.

I hope those provide some inspiration.

According to Merriam-Webster, intimidate means "to compel or deter by or as if by threats." Therefore, if someone was deterred from doing something due to fear of something bad happening, they would have been intimidated.

Petrified, if fear is implied. Anchored as well. Anything denotes lack of movement or action, as long as fear is implied.