Usage of the preposition "out of"

[Duc]

Could you explain to me why my teacher put the preposition "out of" in the blank:

She don't tell the police about her cruel husband .... fear that her family would know.

Thank you so much!!!
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Don't see your shade think you are great

[Pamela]

It's equivalent to 'because of'...

[Yankee]

[Duc]

But why don't we use "for" or "due to" instead of "out of"?
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Don't see your shade think you are great

[Yankee]

First of all, the expression "out of fear (that)" is a common idiomatic expression.

Theoretically, 'due to' might be used, but only if you added the word 'the' (i.e. "due to the fear that ..."), in my opinion. However, that wouldn't sound terribly natural. In addition, many grammarians say that 'due to' can only be used as an adjective. (It functions as an adverb in your sentence.)

I don't see anything wrong with using 'for' (i.e. ... for fear that...). In my opinion, that would also be OK.
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