Back to the subject of possible flaws, I beg very respectfully to differ on the notion that Jack's behavior when he told Ennis Aguirre had come back to say "bring 'em down" was out of character. I think it was completely in character. Jack was an eternal optimist - as some have said, he just figured he'd see Ennis again. To me, it didn't occur to him that he wouldn't until he watched him in his side-view mirror as he drove away.
I actually think that had Jack gone off about Aguirre, having to leave early, and all of it up on the mountain, that would have been terribly out of character for him. But maybe that's just me?
Good point, Barb, about Jack's concealing his emotions. Whether it's because he's easygoing and lets things roll off him, or because he doesn't want to trigger Ennis' startle point, or because he's accustomed to hiding his vulnerabilities (maybe originally from his dad?), or because that's just his way of dealing with bayd news, I can't say. I'll leave that analysis to Jackologists like yourself.
But again very respectfully (and BTW, isn't it amazing how much nicer disagreement seems when preceded by that R-word?) even assuming that Jack
did figure he'd see Ennis again, I still think he's insufficiently upset. Imagine falling in love with someone, spending one passionate idyllic life-changing month with him, just the two of you together in a wilderness paradise. You're looking forward to another month of bliss. But then, abruptly and unexpectedly, it's called to a premature halt.
Even if you do expect to see him again, you're not sure exactly when, there are no guarantees (Jack knew about Ennis' impending marriage, and there'd been no mention of changing that plan), and at best your next encounter might be a whole year away -- hell, even if you're absolutely
sure you'll see him again, but not for a year -- wouldn't you be distraught? I know I would. Me, I'd be distraught even if the idyll had lasted through its whole scheduled term.
Jack could have welcomed the opportunity to join Ennis in trashing Aguirre; he'd done it before about the sleeping arrangements and the beans/sheep. And, being able to read Ennis fairly well, you'd think he might realize why Ennis was so upset and try to gently broach the subject.
The best way I can think of to fit this behavior into his character is that he
knows why Ennis is upset (he looks like he might, when he gazes out at Ennis sulking just before heading over to lassoo him) but, again always leery of that startle point, he wants to be tactful and avoid addressing it directly.