What question was the cause of Ivan's moral sufferings?

Ivan's primary character flaw is that he lets other people define him. He has no personal moral compass rather he relies on others to dictate his reason and judgment. Ivan views the aristocracy as the epitome of civility. He is drawn to the lifestyle and the people who inhabit it. Ivan merely tries to mimic these people without understanding his real motivations. Ivan is all about the optics. He takes a wife because he feels that a young mobile man of substance should have a wife. He buys an expensive house in the city not because he would like one rather because the appearances validate him. This is why he dies such a sad man.