Ideals are what your logical constructs see as an optimal situation or outcome. We all have them. Reality however is composed of many peoples ideas of ideals as well as things that cannot be fully mastered as of yet, for example the universe and its laws of nature.
When your ideals are crushed between realities big fat gnashing teeth you become upset as your projection was wrong. This means that your logical constructs projected an incorrect outcome or situation. When this happens you become upset or frustrated.