Very interesting discussion.
It has made me wonder if the tears that Lureen (almost) sheds during the phone call, were out of some genuine affection towards Jack, or more out of a memory of what could have been.
I never really got the impression of there being any great love between Lureen and Jack, maybe lust in the beginning which led to a familiarity. Convenient for them both, Jack had his own life beyond the marriage - perhaps Lureen did too? Who knows.
The banter between them, when Jack can't find his parka, intrigued me too. There was no real nastiness or intent in the argument - not that i saw anyway, more an apathy. It was as if some ground had been reached where Lureen would voice her feelings, (the comment about Ennis never coming to Texas), but she wouldn't make demands on Jack. Maybe this showed her lack of feeling? Maybe she was pretty content with the way things were, Jack having his own life and she having hers, but i still get confused by the phone call at the end. Would she have become so bitter if she didn't care?
LOL, sorry for all the questions, this subject has really intrigued me. Thanks for strating it Patriot1 
I can think of one reason she might have become so bitter. Let me offer it to you and see what you think.
When she met Jack she knew her dad would not like Jack. He was just a poor bull rider that wasn't very good a bull riding. Just not the type of guy her dad would like. She wanted to get back at her dad so she goes after Jack, getting him interested in her, the pretty and rich young girl. She then gets Jack into the back of her daddy's car, another thing against her dad, and intends to get pregnant so she will have to marry him. She sees that Jack is interested in her and tells her "fast or slow I like the direction your going", intercourse.
She gets pregnant, marries Jack, and makes her father angry. Mission accomplished. She then becomes involved in the business and turns all her attention to it figuring if Jack didn't like it he could divorce her. Unknown to her, though, this was fine with Jack and a friendly relationship develops. You do your thing and I'll do mine. Just don't let your thing interfear with the business.
Then, she finds out Jack was having a relationship with another man, Randall, and was killed because of it.
This had to be humiliating to Lureen. Better Jack have a relationship with "Chatty Cathy" than "Chatty Cathy's" HUSBAND.
Then, Ennis calls. She recognizes the name as the fishing or hunting buddy Jack has been seeing for the past 20 years. She also knew that Jack's favorite place was Brokeback Mountain but she never knew why it was his favorite place or even if there was such a place as Brokeback.
Then Ennis lowers the boom on her. Ennis confirms there is such a place as Brokeback and ONE summer he and Jack herded sheep up there. Suddenly, and without warning, Lureen finds out that before Jack met her he fell in love with Ennis and because he was in love with Ennis he fell in love with Brokeback Mountain, the place where they had met. And, for 20 years Jack and Ennis would get together twice a year to consumate his love for Ennis.
This HAD to have hurt her pretty little rich girl ego if nothing else. He never loved me. Before he met me he was already in love with someone else, and it was with a guy at that. That little bustard (sic) was using me to get a comfortable life!
Wow! Talk about humiliating!
Anyway, that is how I see it and I offer it to you to cogitate on.