Which verb should I use that means to have somebody's trust for a long time? [closed]

What is the right verb for when we want others' trust for a long period? Do we keep, retain or preserve their trust ... ?

Example:

By speaking only the truth I can ... their trust for a long time.

For sure, all of the above suggestions are here or there used. Google Ngram seems to confirm this. But I want to know which one sounds the most idiomatic.

Solution 1:

To keep their trust , or retain, their trust means simply that you will continue to be trusted by them. It does not imply any action on your part.

To preserve something usually means to take some action that will have the effect of keeping it.

In the example given:

By speaking only the truth ...

you are taking some action (telling the truth) to achieve your purpose, that of keeping, or retaining, something. The action you are taking is a method of preservation, the tactic by which you intend to keep their trust.

So

By speaking only the truth I can preserve their trust for a long time.

is most appropriate here. You are explaining by what means you consciously and deliberately intend to hold on to their trust. You are revealing your cunning plan.