B. M. Bower 
Lonesome Land 

Valeria had come to Montana to marry a cowboy named Manley, expecting a future full of companionship and bracing freedom, lodges with great fireplaces and bearskin rugs, manageable cattle and sleek horses, and dazzling sunrises. If Val had known what was really waiting for her, she simply wouldn’t have gotten off the train. Oh, the country was impressive, but it could be cruel in winter and lonesome for a woman stuck on a ranch miles from the nearest neighbor. Val is cast into circumstances that test her temper, strength, and sanity. Married to an alcoholic, she is forced to revise her back-East notions about men and women, duty, and the West itself. She goes from romanticization to "blind unreasoning terror of the empty land" to decisive action. (Goodreads)