Everything changes. Situations. People. Ways of reacting. Just Everything.
Sometimes, it's acceptable. Sometimes, it's not. When we have expectations attached to circumstances, it gets worse. 'cause, the otherwise is not really acceptable. Sometimes we overdo the same thing, to work things out the way we expected, but when the don't stand upto it, the stand point collapses.
That's how it happens everytime. Trust is not important, what matters is what is in the head.
Everything is fragile. So it falls apart.