This expression on Jack's face was enuff to earn him the Oscar right there, IMHO. Jake must have been inspired by the story, which goes, in part:
"Ennis's breath came slow and quiet, he hummed, rocked a little in the sparklight, and Jack leaned against the steady heartbeat, the vibrations of the humming like faint electricity..."
and then Annie Proulx winds up:
"Ennis, dredging up a rusty but still usable phrase from the childhood time before his mother died, said, 'Time to hit the hay, cowboy. I got a go. Come on, you're sleepin on your feet like a horse," and gave Jack a shake, a push, and went off in the darkness. Jack heard his spurs tremble as he mounted, the words 'See you tomorrow,' and the horse's shuddering snort, grind of hoof on stone."
This is the last time they ever see each other. How appropriate that it ends with no sex, but sexual imagery, suggesting to the aware reader that the two men united in spirit. There is also the timelessness of childhood and the experience of unconditional love that comes from a mother.