I've often heard that what you dislike in others is a reflection of you. I don't agree with that but I do believe that what we expect from others is a reflection of the way we behave in similar situations. I've found this to be true way too often to put it down to an aberration.
We project our own ways of being onto the world around us and then look for evidence in people's words or actions to support our belief. Anything can be twisted to provide the evidence we need in that moment.
What we should be looking at though, is past behaviour. It's not fair to constantly expect a person to prove themselves and their intentions. It's abuse. If past behaviour shows you that a person has no respect for you, then move the hell on. If past behaviour shows you that a person will bend over backwards to take care of you when you hit a low point then value them. Don't expect them to constantly validate that judgement. Give them credit for what they have already done.
When you are constantly watching someone's actions and waiting for them to trip then it's not their actions that are a problem. It's your baggage that needs to be offloaded so that you can build a future without bitterness and resentment.
I suppose it's similar to raising the same infraction over and over again when arguments arise. If there's nothing new to raise then why in the name of all that is holy are you continuing with the fight?
People make mistakes. If it feels right, forgive them. People make the same mistakes more than once. Those are called choices. Do what is best for you. But for crying in a bucket! If a person is trying their level best to move up, to move forward, to better themselves then don't you dare keep flogging them for the crap in the past. The people who are prepared to work to become their best selves are the ones who deserve our praise and encouragement. Mistakes will still happen - we're not infallible. Sometimes the mistakes are made by people who truly love us and those are the people we need to help through their mistakes.
Life is not about perfection and love is not about all our needs being met. It's about looking at our friends, family and partners and accepting that they are who they are and then loving them in all their messy glory. So hold up your mirrors today and then smash them... let people show you who they are without project your expectations onto them.