The story has overlapping themes, but a most significant one is loss of innocence, which is symbolized by the loss of the ring.
When the story starts, the newlywed Lovisa (Lise) believes she can never have any secret from her husband and thinks to herself as he talks about sheep,...
"What a baby he is! I am a hundred years older than he.” When she hears the story of the sheep thief, a "pleasant little thrill" runs down her spine. She decides to hide from her husband as a game, thinking it would show him "what a void, what an unendurably sad and horrible place the universe would be when she was no longer in it." Life is simply a child's game to this young woman with "golden curls." We learn that "she had never in her life been exposed to danger."
When Lise then encounters the sheep thief in the "sylvan closet" of the small alcove in the grove, in what amounts to a symbolic rape, the thief's "knife" points up at her "throat." Later, "he put the knife back in the sheath by his belt." He kicks away the wedding ring she offers him, not interested in this symbol of faithfulness and love.
The irony of Lise's earlier thoughts emerge as she joins her husband after her encounter in the alcove. She had imagined she would never have any secrets from her husband. Now, in her loss of innocence after her sexualized encounter with death, she keeps secrets from him about what has happened to her and where she might have lost the ring. From a person who was "wonderfully happy," she moves to new, more sober thoughts:
With this lost ring she had wedded herself to something. To what? To poverty, persecution, total loneliness. To the sorrows and the sinfulness of this earth.