There was a poem I read years ago that I can't remember the name of. The setting is rural, possibly set in 19th or 20th century United States. A young man, possibly even a teenager, suddenly has some major medical problem. His sister calls for the doctor, who gives the young man some ether and tries to save him, but to no avail and he passes away. The most striking thing I can remember is that at the end of the poem, possibly the last line or two, goes something like "And they all went about with their lives/For it had not been them who had died". Obviously, that's not the exact line, and I can't even remember if it was in rhyming verse, but the poem did conclude with something to that effect. The only other notable thing I can remember is that the poem was at most a few stanzas.
You are most likely talking about Robert Frost's poem, "Out, Out-", which fits your description and ends, "And they, since they/Were not the one dead, turned to their affairs."