Why was Mrs. Sappleton bored with Framton?
Mrs. Sappleton is bored with Framton Nuttel from the beginning. He is just someone she is obligated to entertain because of some very tenuous connection with his sister dating back four years. They have nothing in common to talk about. He talks about his ailments, while she "rattled on cheerfully about the shooting and the scarcity of birds, and the prospects for duck in the winter." Framton cannot talk about that subject because he knows nothing about it and because he thinks his hostess is insane.
Probably what happened was that his sister, who stayed at the rectory, asked the minister to introduce him to a few local people, so Mrs. Sappleton is obliging the minister and may not even remember Framton's sister. Furthermore, Framton is an inhibited, boring person. At the end of the story she says: "...could only talk about his diseases." No doubt Vera makes up her ghost story because she finds Framton boring and would like to shake him up a little. We can't help liking the mischievous Vera. She is not old enough to tolerate the kind of boredom that her aunt has had to accept as part of the obligations and proprieties of upper-middle-class domestic life in the country.