Along these same lines, I always find it particularly poignant when Lureen says to Ennis, "I thought it was someplace to drink. Jack drank a lot." That last bit stabs me in the heart. My mother turned to drinking to self-medicate after the love of her life, my father, left her when I was 2. It took a few years, but by the time I was in kindegarten, she was a full-fledged alcoholic. It makes me picture him in the house with Lureen and Bobby at night after work, missing Ennis so much he can hardly stand it, pouring himself one whiskey shot after another (I don't think he'd just pull on the bottle in front of Lureen) until he stumbled to bed drunk.
And I agree with Victoria that Don Wroe was a co-worker, not a friend, to Ennis. I kind of see him as a boss, really, which would delineate them even further. I figure he owns/owned a ranch Ennis worked on. I could see a ranch owner a) having the money to own a hunting/fishing cabin and b) offering it to Ennis because he's his hardest worker and seems to be the type who likes his solitude. I agree that Ennis had no other male friends than Jack, partly because of his homophobia and fear of people thinking it was something else, and partly because Jack was all the friend he needed.