What experience in this section does Perry consider to be unreal?

Since you do not designate which "section" you mean, let's just say this. Richie Perry's experience in Vietnam seems unreal in every way. Although he faced a deprived and dysfunctional childhood with his alcoholic mother, he believes that his military service will help him find a "way out" which will make his future better. The brutality of war, for which he was completely unprepared, makes him ask questions which no one can answer for him. He does mature while he deals with these unrealities, but the truth is, when he finishes his service and returns home, not much has changed. His future still seems bleak and the horrors of war have not moved him any closer to understanding the way the world really works.