What is the short story, "The Resemblance Between a Violin Case and a Coffin," about?

One of Tennessee Williams' finest short stories, "The
Resemblance Between a Violin Case and a Coffin" tells the story of a brother and sister
who find themselves falling for the same young man. Tom is a 12 year old boy who
suddenly finds his older sister (who is never named) drifting away from him. She is
feeling the first effects of puberty, though Tom doesn't recognize this. A talented
pianist, Tom's sister begins practicing for her upcoming recital--a duet with Richard, a
handsome young violinist. She becomes flustered whenever she's around Richard, and Tom
suddenly realizes that he has sexual feelings for the boy as well. Tom's sister plays
atrociously at the recital, but Richard covers up her mistakes with his own
improvisational skills. In the end, Tom's family moves away, and they eventually learn
that Richard has died. The title refers to the narrator's comment about the similarity
of Richard's violin case and a small coffin. The story was based on the author's own
life; Tom's unstable sister is based on Williams' own sister, Rose, who had a mental
breakdown and was later confined to a mental institution.