Why did The Giver apologize to Jonas after sharing the memory of war?

In Jonas' community, the people live a peaceful existance without violence or pain. War no longer exist, because there are strict rules that everyone follows and people in the community do not have contact with others outside the community, so there is no one to come into conflict with. Therefore, Jonas has never experienced anything like the horrors and pain of war before, and after the Giver shares the memory with Jonas, he apologizes because he knows that it has shocked and pained Jonas to receive this memory.