We didn't see two different films; we saw the same film totally differently. That's why BBM is a classic in the making; it is a tragedy capable of invoking incredibly different reactions from different people. But what is the tragedy, ultimately? Is the tragedy that Jack and Ennis, two arguably homosexual people, never had a chance to spend their lives together? Or is the tragedy that Jack, a closeted gay man, spent twenty years of his life trying to convince a dysfunctional, emotionally-crippled and psycho-sexually confused man that he was really gay? The romantic 'believer' in me wants to embrace the former interpretation, but the experienced post-Stonewall queer in me remains open to the latter interpretation.
I agree that you can interpret the movie in many ways. Another one would be that it is a tragic tale of how one man´s inner fear stops him from making a go with the man he loves, and ultimately looses him because of it.
And how we interpret it much due to our own experiences and what we can relate to in the story.
However, I do think, there´s a main story here that is freestanding from our individual interpretations, and that is a story about how Jack and Ennis can´t bee together because of a homophobic society. What bothers me about the other interpretations is that they leave this part out and focuses on what, for example, is "wrong" with Ennis etc. To me, this is to miss the main point that Annie Proulx is trying to make, and it dimishes the storyline. Annie Proulx has said herself that Brokeback is a story about a homophobic society. She has always been interested in examining how different enviroments, areas, cultures effect the people living in them, and Brokeback is another example of that.