We all are human and have flaws.
Forgetting to do something I will not perceive as breaking trust.
How many times we forget things either by distraction or for having a lot in our plate?
I can't trust someone that gossip or that talk down on other people.
I can't trust people who share information that was confined to them.
I can't trust people that lie on a regular basis.
I can't trust people who usually cheat, if they do to another, they will do it to me.
I can't trust a man or woman that sleeps with people already in a committed relationship. Not trustworthy.
I can't trust people who spread false information about others.