The thing is: you might be right to trust someone at one point, but they can change."
"+ in between they must be drifting from trustworthy to not. But you can't tell how far they've drifted until it's too late.

Because he could not afford to fail, he could not afford to trust.

I just go in there. I like to trust my (catchers) back there, I'm not a guy that stands out there and shakes them off.

You have to trust or you're only living half a life.

It isn't fair how I doubt him, and I wonder if he'll ever gather that my loss of faith extends further than I'd ever known it would, severing lines of trust and leveling my confidence like a city-flattening tornado.

Ginny!" said Mr. Weasley, flabbergasted. "Haven't I taught you anything? What have I always told you? Never trust anything that can think for itself if you can't see where it keeps its brain?