What is the theme in Brokeback Mountain by Annie Proulx?

Intolerance is a major theme in this story. The concept of masculinity in the American West does not include homosexuality. Western legends, in literature and film, glorify men who display courage in the face of overwhelming odds and who as pairs ride off together into the sunset or as individuals return to women waiting patiently in the schoolhouse or in the farmhouse. These mythic stereotypes reflect a predominantly conservative set of values in the American West that refuses to recognize as natural a sexual union between two men. Proulx placed her protagonists in this intolerant setting and traces the suffering they experience as a result.