At times stern, at other times patient, at times perceptive, at other times in sad denial, Olive Kitteridge, a retired schoolteacher, deplores the changes in her little town of Crosby, Maine, and in the world at large, but she doesn’t always recognize the changes in those around her: a lounge musician haunted by a past romance; a former student who has lost the will to live; Olive’s own adu…