Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Remarkably, this story of two adulterous lovers contains neither a moral nor a moral judgment. The narrator is simply objective. He tells it like it is: this is what Anna thinks, this is what Gurov thinks, and this is what they do. Even in the story's introduction, when Gurov is introduced in all his chauvinistic glory, the attitude is devoid of condemnation:
He had begun being unfaithful to her long ago – had been unfaithful to her often, and, probably on that account, almost always spoke ill of women, and when they were talked about in his presence, used to call them "the lower race." (1.4)
Sure, we might feel like condemning him, but the point is that the narrator doesn't.