The 26 love stories in this anthology, from Anton Chekhov’s “The Lady with the Little Dog” to Alice Munro’s “The Bear Came Over the Mountain,” are not happily-ever-after affairs. Instead, as Eugenides writes in the introduction, “Love stories depend on disappointment, on unequal births and feuding families, on matrimonial boredom and at least one cold heart.” Eugenides, a professor of creative writing at Prince-ton, is the author of the Pulitzer Prize-winning novel Middlesex.