This scene and the last time Ennis and Jack were together arguing were the two scenes I had the most questions about.
Lureen said three things that I didn't understand her reason for saying them.
1) When Ennis says that is why he was calling, to find out what happened. Lureen says, "Oh yah." What did she think he was calling about...the weather report? Why the "Oh yah."?
2) Lureen is talking to one of Jack's friends. Why did she feel it was necessary to tell him that Jack was only 39 years old?
3) And, why did she say, "...about the ashes I mean."? Did Jack have other wishes that Lureen was aware of?
During the argument between Jack and Ennis, I couldn't understand how or why Jack's statement, "I did once" could or would bring on such a threatening response from Ennis about Mexico. What, I asked myself did one have to do with the other? Just seemed like every time Jack brought up living together Ennis' reaction became more violent. In the beginning it was, "It could be like this, just like this, always." and "I told you it ain't goin' a be like that", to "Perhaps you should move to Texas" and Ennis gets mad, to the "I did once" in the parking lot and Ennis going off on a tangent about Mexico.
Good points Patriot, they made me wonder too... here's my 2 cents:
1) regarding Lureen's "oh yah" - personally, I believe that Jack was murdered and the whole accident story was just a cover, probably because Lureen and her family didn't want people to know the real reason. When she gave the details to Ennis I felt like there was something technical and monotonic in her voice, like she was going through a paragraph she had memorized by heart... so I interpreted this "oh yah", said with a little sigh, as something like "oh yeah, time to go through the cover again..." just my take.
(EDIT: tpe, I only got to read your response after I posted mine, and now I see that we got the same impression from that line!
)
2) why would she mention Jack was 39 - you're right, it doesn't make any sense, his friends should know how old he was. I think this is the point where the filmmakers wanted the audience to know how old Jack was, to give the viewers the time-frame, so they just had Lureen say that and maybe they didn't realize themselves that it wasn't making much sense.
3)"about the ashes, I mean" - again, it leaves me puzzled too. I'm not sure why Lureen sees a need to clarify this point to Ennis. as for other wishes, the only wish Jack had IMO was to be united with Ennis, I don't know if Lureen has realized that by this point but if she did, maybe that was the other wish she was implying to?...
Now, as for Ennis's reactions to Jack's statements. While I was reading what you wrote, it hit me that you actually gave the answer to this one yourself, and allow me to quote you:
"Just seemed like every time Jack brought up living together Ennis' reaction became more violent". Ennis was a homophobe, he had internalized this homophobia since childhood. And he had that terrible, traumatic memory of Earl in the irrigation ditch. He knew what happens to two guys who're living together. He had also tried to believe that he wasn't queer, and he could never accept that part in himself that loved a man. for him it was "this thing" that grabs hold of him, he never called it love (at least not while Jack was still alive), he just couldn't handle that thought. Whenever Jack brings up the subject of living together, it touches Ennis in a very sensitive spot: first, if they were to live together, then it's much more than just "this thing". that would make them like Earl and Rich, and he knew they were queers. He can't handle that. second, it reminds him of his childhood trauma and what happens to guys who choose to live together, and this is his biggest fear. therefore, since this subject is so sensitive and loaded to him, whenever Jack brings it up Ennis feels uncomfortable and it brings out the violence in him.
When Jack says "I once had", it just brings it all up. the "better idea" that Jack once had was to live together, Ennis knows that. it brings up all the fears, all the internalized homophobia. Jack wanted to live with him because he loves him, because Jack is gay, but Ennis can't deal with this thought, because what does it say about
him? It's a trigger and again, the violence comes out.
I hope I managed to explain myself...