Hi again HiAltShag.

Just to clarify, I don't mean to say that the work ethic would have any influence on their 'ability to overcome strong male sex drive and develope resistance to cheat'. I don't actually think the two are related. I was just noting some of the reasons I thought their relationship could work (
if they decided to be together). Their ability to work well together being one of them.
As to the strong sex drive and temptation to cheat, again I don't actually think that's an issue. I believe that Jack only pursued it elsewhere because he couldn't have Ennis. I have no reason to think that he would have become 'easily smitten' with anyone else if he had Ennis with him (of course, that's an unknown variable in any relationship so who can predict - it's just my sense of things).
I agree with you 100% about Ennis being ashamed of his relationship with Jack. And Jack knowing it.
But I don't think that has anything to do with whether or not he respects Jack. I think that is about his attitudes about homosexuality and the way he was brought up to think it was wrong. I see no evidence to indicate he didn't respect Jack. And those occasions when he was dismissive (like in the river scene when they're talking about going to Texas) are, I think, Ennis's defensive habits at work.
As to Alma, I guess I just see this character differently than you. I don't think she was particularly sophisticated. She was a small town girl, with apparently little advanced education, who was raising two kids in a little town and didn't get out much. I think with Alma, what you see is what you get. But, as I said, that is just my impression of this character. As with all of the secondary characters, we have to kind of fill in the blanks for ourselves from where the SS and screenplay left things vague.
It's harder for me to pin down my sense of your impression of Ennis. I think we agree on a lot of elements of his character. But I don't know that I think he had much concern about where he fit in with mankind in general. As you said, he wanted to have a ranch of his own somewhere. My guess is the more isolated the better. He wasn't, by his own admission, very social: "Hell, that's the most I've spoke in a year." But even if he had attained that goal while married to Alma, I don't think he would have necessarily been happy with her. He couldn't get Jack out of his mind (or his heart). And if he could've had a ranch with Jack without having to worry about the scorn or the tire irons, I think he would have. Because it was Jack he wanted to be with. Whether he could bring himself to admit it under the circumstances in the story or not.