I understood why you wanted me to write more. When I had time to think about it, I just realized I didn't have anything more to say than what I'd already said.
It's looking to me that what we have here are two different views of the world, and of people. Of course Ennis doesn't stop and think about why he's reacting,. He just reacts. And I'm prepared to admit there is a trigger involved here--Jack's implicit threat. What I'm not prepared to agree with is that there is only one reason, or even one most important reason, that he collapses because I don't see people and the world that way. On the other hand, if your "most important reason" is my "trigger" then maybe we're just arguing semantics, as I think you yourself suggested somewhere back up the line here.
If you'll forgive an analogy from my own life, the worst "collapse" I've ever personally experienced was at my boyfriend's funeral. I sobbed on the shoulders of a friend like I'd never cried in my entire life, not even at my mother's funeral. The funeral--my boyfriend's death--may have triggered my reaction, but even here, there was also fear involved because my boyfriend died of AIDS (as it happened he didn't give it to me), and I'm just not prepared to assign a more or most important cause to my own reaction. I feel it's pointless.
But I do find it interesting to try to parse out the several reasons, or causes, for what happens, and in Ennis's case to try to account for the vehemence of his reaction. And it's certainly true that if we didn't love the move we wouldn't be here. It would be just too weird otherwise.
Yeah, and it's weird enough as it is!
Another reason, I realized later, that I find it worthwhile to think in terms of a most important reason for Ennis' breakdown is that I see it, coming as it does at the climax of one of the movie's "most important" scenes, as closely connected to fairly central questions surrounding the meaning of the movie. For example, if you believe Ennis has recognized his love for Jack all along -- as I do and, judging from past posts, you don't -- then the threat of losing that love may be a more important reason. And if you think it's possible that Ennis already is starting to recognize, if not fully accept, the nature of his own sexuality, then homophobia is less important.
I would never deny Ennis' homophobia, though, or try to oversimplify his character. It's all swirled together, all right. The complexity of characterization makes the movie rich and compelling and makes Ennis and Jack so real.
And not to resurrect a debate, in any case. I accept that you and I and others have different macro-interpretations -- no doubt influenced, as you say, by our different views of human nature and life experiences.
I'm really sorry about your boyfriend, Jeff.