Well, it might be inspired by the social and cultural aspects of the time it is set in. The harshness of the ranch life, the masculine ideals, and the hidden emotions could all be part of the real - life inspiration. Also, the relationships between different classes of people in that rural and somewhat isolated environment might have contributed to the story. The movie seems to explore the power struggles and unspoken feelings that were probably common in such a setting in real life.
The real - life inspiration likely came from the ranching and cowboy culture of the American West. It could also be related to the complex relationships and power dynamics that existed in that era.