Gene has an explanation for this in Chapter 2. He says,
Bombs were completely unreal to us here, not because we couldn't imagine it - a thousand newspaper photographs and newsreels had given us a pretty accurate idea of such a sight - but because our place here was too fair for us to accept something like that (30).
He goes on to say that he and his fellow students were "completely selfish" (30) and that there were very few places in the world during this period where anyone had the luxury of being completely selfish.
Gene also tells us that the professors were more "indulgent" (24) than they would have ordinarily been. He says this is because the boys "reminded them of what peace was like..." (24). This indulgence on the part of the professors also contributed to the boys' feeling that the war was not "real."
Even though we are bombarded constantly with information today, from the Internet and from radios, televisions, and newspapers, it is still difficult for us to see all of the terrible events occurring in today's world as "real." This is even more true of young people than of older people, particularly when those young people are at a small private school in a rural setting, far away from the world of war. Those of us who live in the United States are even more prone to this failure of empathy than those who live in other places because we have experienced so few wars on our own soil.