Why do we so often expect people to be perfect? Why are we so often surprised when difficulties arise and conflict (over the littlest thing) arises? Why do we expect people to be masters of all wisdom and knowledge?
I find that most of the frustration that comes in our lives comes when we look at another person and think, "Come on, they know better than that!" Of course, in reality, this is just being egotistical. It is egotistical because, in reality, aren't we more upset that we are inconvenienced rather than that people we know and care about are upset, are in a difficult time (even if it is of their own devising). It is egotistical because we will look down upon people in their folly. . . but the things that we get worked up about, well, those are the "really" important things.
Why do we set expectations for others when we know that we ourselves fail so often? Perhaps it is precisely because we have lulled ourselves into forgetting our failures. Perhaps it is because we will ignore the Law when it hits too close to home.
My advice - you cannot control the actions of others - but when others frustrate you, examine yourself, confess your own sin, and delight again in forgiveness.
Now, if only I were perfect in doing this myself!