Reality in writing

In striking the balance between my responsibility to my reader, and that to my writing, an important question has come to my attention. How real does the writing need to be so that the reader can relate to it? From what I'm experiencing, not very. For example, real people shift moods rapidly and often without explanation. Real feelings are rarely streamlined and often bounce around and conflict. In writing that often results in "I don't get it" from the reader. We always want to have the why-s answered or at least asked properly. But so often there are no why-s, there are no explanations for our life experiences. Should that not be written about because the reader isn't inclined to digest it?