Interesting, one other exchange from Macbeth that I often recall in discussions of this scene:
When Macduff learns that Macbeth has had his wife and children murdered, he initially collapses in grief. "Dispute it [i.e., "take it"] like a man", an aide admonishes him.
"I shall do so," Macduff answers. "But first I must feel it like a man."
One of Ennis' failings in the story is that while he has emotions, he doesn't always consent to feel them, if that makes sense. There seems to be quite a sea change in that sense, not only in the last scene but in the two preceding it. In the Macbeth scene, "man" is used in two different senses: masculinity and humanity. Ennis in the last scene appears to be on the verge of coming to terms with both.
Yeah, I know this is off in the ozone.... 
Hey, no way Marge...
you're not out in the Ozone (what's left of it!); what you've said is very true about Ennis. Not to blame him, because I feel Ennis wants to express more, but hasn't had the chance to learn how! Also, Ennis is a man "of present means and ways", of necessity due to his background and life situation.
He wasn't able to "dream" like Jack. His main focus was on providing for himself and his family after he was married and then there was, Jack, the other "focus" of his life. He was really torn in two, trying to be true to both his family and the true love of his life.
Ennis is also a man enslaved by conventions and fear. He knew what he was taught as a boy: how things ought to be and what can happen if one goes against the way things ought to be. His fear of what could happen, "Two guys livin' together, no way!" was part of the tragedy of his life and, of Jack's life too.
Social conditioning and fear play a large part in most human lives. On the other hand, Jack was more imaginative and perhaps a bit more intelligent too. He had vision, could "see" a way to be with Ennis...."We could've had a damn good life together, but you didn't want it! So what we got now is Brokeback Mountain!" The contest of wills and the strong need and attraction they had between them is what makes the tension, the drama so unforgettable.
But you've also hit upon this "
Masculinity and Humanity" issue in men too! How often have we heard, "Take it like a man!" when what is meant is "Don't be (weak) like a woman"?! What a crock! There are strong women and weak men, and men, when they can express their humanity fully, can express sadness, grief and loss with tears.
Big Boys Do Cry! It's a very good point, Marge.
Thanks,
Rayn