Here's some of my thoughts on "Brokeback Mountain":
This is a lovestory between two persons who are unable to break with each other, and unable to develop their relationship into something truly worthwhile and satisfying.
They were meant to be soul mates, but mostly due to their own failings, that doesn't happen before one of them is dead and gone.
Jack, the most overtly passionate one, wants to develop their relationship into something more, but is also hopelessly unrealistic. He has some half-baked ideas of buying a ranch and live there with Ennis, yet given their abysmal finances and the attitudes they'd have to face in the mid-West, the whole idea is basically ludicrous. As the years go by, their brief, intense encounters are clearly too little for Jack's passionate nature and he degenerates into making trips to Mexico buying sex when the need becomes too great. His gradual incaution (in line with his lack of realism) leads eventually to his death.
He knows he ought to break up from Ennis, but precisely because their encounters are so infrequent, when they do occur they are far more intense than they "should" be. Basically, he doesn't dare to break up with his lover for fear of the loneliness and emptiness that action would bring him.
Nor does he dare to push Ennis too hard in fear of losing him.
Thus, he's stuck with Ennis, however unfulfilling the situation is for him.
Ennis, on his part, experienced bliss on Brokeback Mountain and seeks more to relive it time and time again than trying to develop the relationship into something different. Essentially, he fears that if he were to commit himself further, then their relationship wouldn't be a series of Brokeback Mountains anymore. He is too unimaginative and timid to convince himself that such a deeper commitment is what he is needing and that would develop and enrich him as a person.
Instead, as the years go by, he slinks into an aimless, meaningless existence with increasing frequency of drinking bouts and brawls, only bearable due to his meetings with Jack.
Effectively then, Brokeback Mountain is for both of them as much of a prison as it is an escape from reality.
Or, perhaps precisely because it IS an escape from reality, they remain incapable of dealing with real life in any constructive manner.