In addition to Stiva and Nikolai, another character in this work declares, "I shall still be as unable to understand with my reason why I pray, and I shall still go on praying" at the end of the work, though he had earlier failed in his courtship of Ekaterina Shcherbatskaya.  
One character in this work is forgiven by his wife for an affair with a governess before beginning one with a ballerina.  Another character in this work is a sickly, thin man who eventually starts dating a reformed prostitute, Marya Nikolaevna.  In addition to Stiva and Nikolai, another character in this work declares, "I shall still be as unable to understand with my reason why I pray, and I shall still go on praying" at the end of the work, though he had earlier failed in his courtship of Ekaterina Shcherbatskaya.  Another character in this work rejects Ekaterina before having an affair with the title character and moving to St. Petersburg.  For 10 points—name this work in which Levin marries Kitty and the title lover of Count Vronsky throws herself under a train, a novel by Leo Tolstoy.
One character in this work is forgiven by his wife for an affair with a governess before beginning one with a ballerina.  
Anna Karenina