Who is Helen from The Nick Adams Stories and what is their importance?

Helen is Nick's wife. Little is known about her, and she appears only briefly in "Wedding Day" when the newly-married couple are rowing to a cottage where they are going to spend their honeymoon. The two spend some time apart apparently (for reasons unknown), as Nick spends at least a few months with his friend George in Europe. In "Cross-Country Snow," Nick mentions that she will be having their first child.