Ran across this quote today from Helen Keller that I think sums up what I have been trying to say to people about trust - when someone asks, "how can I regain the trust in my spouse?" and I say that you have to accept risk, that the things we do to remain "safe" do not protect us.
Quote: Security is mostly superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. The fearful are caught as often as the bold.