JACK: Can't wait till I got my own spread, and I won't have to put up with Joe Aguirre's crap no more.
Early on, the movie establishes Jack's hope for independence and a life of his own. However, at this point, we don't know that Jack would want to share this life with Ennis. Maybe Jack doesn't even realize that yet.
ENNIS: I'm savin' for a place myself. Alma and me, we'll be gettin' married when I come down off this mountain.
Ennis has different, but similar, plans. He wants a family. Perhaps this helps Jack realize that Ennis would be a good match for him, if only he would ditch Alma for Jack.
JACK: Yeah, I'm commutin' four hours a day. I come in for breakfast, and go back to the sheep, evenin' get 'em bedded down, come in for supper, go back to the sheep, spend half the night checkin' for damn coyotes.
It sounds like Jack and Ennis are rehearsing for married life here, like a cowboy version of The Honeymooners.
JACK: What if you and me had a little ranch somewhere, a little cow-and-calf operation, it'd be a sweet life. I mean, hell, Lureen's old man, you bet he'd give me a down payment if I'd get lost. I mean, he more or less already said it.
Jack never lets go of his early dream to share a ranch with Ennis, but Ennis is always resistant, brushing away Jack's hopes as worthless fantasies.
JACK: "King of the Road."
When Jack hears of Ennis's divorce, he thinks his dream has come true. He believes that Ennis divorced Alma for him. But Ennis is about to shatter his hopes.
ENNIS: Texas? Sure, and maybe you can convince Alma to let you and Lureen adopt the girls. Then we could just live together, herding sheep, and it'll rain money from L.D. Newsome, and whiskey'll flow in the streams, Jack, that's real smart.
JACK: Go to hell, Ennis Del Mar. You wanna live your miserable f***in' life, you go right ahead. I was just thinkin' out loud.
A man can only have his dreams dashed so many times before he snaps. This is the moment where Jack finally realizes that he can never have the life he dreams of with a man like Ennis. He'll either need another dream, or another man.
JACK: Tell you what, we coulda had a good life together, f***in' real good life, had us a place of our own. But you didn't want it, Ennis! So what we got now is Brokeback Mountain. Everything's built on that. That's all we got, boy, f***in' all, so I hope you know that if you don't never know the rest.
Jack is a romantic, and Ennis is too practical to even have hopes and dreams. They aren't a good match. A romantic and a realist is like a hot air balloon falling in love with an elephant. One will drag the other down.
JACK'S DAD: Tell you what, I know where Brokeback Mountain is. Thought he was too goddamn special to be buried in the family plot. Jack used to say, "Ennis Del Mar," he used to say, "I'm gonna bring him up here one of these days and we'll lick this damn ranch into shape." Had some half-baked notion the two of you was gonna move up here, build a cabin, help run the place. Then this spring he got another fella gonna come up here with him, build a place, help run the ranch, some ranch neighbor of his from down in Texas. Gonna split up with his wife and come back here. So he says. But like most of Jack's ideas, it never come to pass.
Jack's dad talks a lot. Jack's dad is also a jerk. He probably wouldn't be like this if Jack were having these dreams of settling down with a woman. It's merely the fact that Jack wants to settle down with a man that makes Jack's dad act this way.