To use the words of a title of Thomas Wolfe's "You Can't Go Home Again." The theme expresses the fact that a person is greatly altered by something as horrific as war; therefore, he cannot return to his home and be what he was before he left. This fact is what causes the main conflict with Krebs; for, his mother especially wants him again to be her boy again and resume a conventional life. Instead, he has to lie to her, for he cannot be the person she wants:
All of the times that had been able to make him feel cool and clear inside himself when he thought of them [what happened in the war]; the times so long back when he had done the one thing, the only thing for a man to do, easily and naturally, when he might have done something else, now lost their cool, valuable quality and then were lost themselves.
Thus, the meaning of the double entendre of the title comes is evinced: The soldier is home (soldier's home), but the home is not the soldier's anymore (not the soldier's home) because he cannot reverse the past.