Background: ag_unicorn says nothing is ever lost by asking for something. I say that it's possible to experience disillusionment and loss of trust by asking for something. He asks if you can lose something you never had in the first place. My reply:
Your responses imply that you think what's in a person's head is not real if it fails to coincide with what's outside a person's head. While that's true in a materialistic sense, it's not at all true in an emotional sense, in my opinion.
Also, your responses imply that trust is singular and binary (you either trust someone or you don't). That's not true for me; I tend to trust people in certain areas and not in other areas, based on their behavior over time.
If I think something is true and base part of my joy in living on that, and then it turns out not to be true, I tend to lose some of my joy in living. (This is a loss that I can repair in most cases, but it's still a loss.)
If I think I have a relationship with someone such that they will handle a request from me with sensivity and respect (note, I don't say I expect them to always grant the request), and they fail to do so, then that can cause me disillusionment and loss of trust.
If I think someone understands me well enough to know how I'll respond to certain requests, and they make requests that cause me pain, then that can cause me disillusionment and loss of trust.
I do think there's wisdom in your statement, but I glean wisdom along the lines of "you know, you might consider when you ask for something 'what's the worst that can happen?', and if the worst that can happen is very unlikely, you might ask anyway, because you might be pleasantly surprised." Not "you can't ever lose anything by asking."