What is an example of situational irony in the excerpt?

“‘Her great tragedy happened just three years ago,’ said the child; ‘that would be since your sister’s time.’”
“‘Her tragedy?’ asked Framton; somehow in this restful country spot tragedies seemed out of place.”
“She rattled on cheerfully about the shooting and the scarcity of birds, and the prospects for duck in the winter. To Framton it was all purely horrible.”
“‘I hope you don’t mind the open window,’ said Mrs. Sappleton briskly; ‘my husband and brothers will be home directly from shooting, and they always come in this way.’”