How do you deal with being disappointed with the other person?

You're under the assumption that others should be all things to you, but that's impossible. Sometimes people have problems; ill health; depression, etc. This doesn't mean they don't like you and you sound overly sensitive. If you feel this way with a certain person then have a talk with them and communicate your feelings. All of us can be disappointed by family and friends, but once you start communication it is often nothing to worry about.