I seem to be experiencing a lot of it lately. Mostly, I've become disappointed in several other people over the last couple of weeks, and it has been depressing me. Therefore, I think (obsess) about it all the time.
The first person, I'll call "Pencil" (so I don't use real names or pronouns), has developed a double standard for the things that "it" can do as opposed to what the other "its" in its house can do. And, Pencil is just acting really immature. There's nothing I can do about it except accept this apparently new side of Pencil and get over it. The people that Pencil is directly affecting need to do the discussing, but Pencil isn't listening, and definitely isn't seeing both sides of the issue. I feel that Pencil is being very selfish.
The second person, Pillow, just doesn't "get" me, and it's frustrating when trying to communicate.
The third person, Parrot, seems so self-involved, that it's a little difficult to be around. Parrot is extremely pompous and opinionated, but otherwise, very smart and friendly.
The fourth person is more like a group of people; they are closed-minded and won't even listen to other points of view. They don't follow tried and true methods, don't speak up when they need help, and completely disregard me as a source of information and experience.
My first reaction (as a result of frustration) is to just ignore it; be numb to it. If I expect nothing from these people, then I won't be disappointed. This solution isn't really a solution. It's just avoidance of a problem. If I don't work through the problem, then it will always be there, at least in my mind. Then again, there is no reason for any of these people to change. They are just being themselves. I wouldn't want someone to try to change me, and I certainly wouldn't want someone to approach me and tell me that they are disappointed in me. My reaction to that would probably be one of anger, and in that state, I would have no desire to help repair the other person's opinion of me.
So, really, disappointment in other people is a conundrum. At least, for me it is. Maybe I'll come up with a solution some day. Until then, I just need to not be so judgmental, and to just try to expect people to be themselves, instead of what I perceive themselves to be.