B.Peter does not clean his sword after battle.
That is your answer
B. How can I avoid this situation?
C. Why do I have to do this?
D. Why is this happening?
they have both been married
they are familiar with Siberia
they are both rebuilding their lives
I believe the answer is: they both have children
In the story, only Ryo has children while Tsuruishi doesn't have any. The story depict a story about the struggle of ryo the world war period. Her husband went missing because he was captured in Siberia and Japan was experiencing massive recession due to the war.