Although I love Jack's mom, I think Alma is my favorite. When we first meet her, she's just a little girl getting married to a guy she obviouslyl, loves, or thinks she loves. She's an innocent and has the whole world ahead of her and Ennis. The two of them playing in the snow shows her girlishness and innocence, again. Then, we see her washing clothes on an old scrubboard -- damn hard work, but doing it and taking care of two squalling babies, just waiting for Ennis to come home. She takes care of the house with no help, no modern applicances, raises two children, provides home-cooked meals and clean clothes for Ennis, and is there for him intimately, even when she hates his preferred position. She does all this, and gets a job working at the store. That's love and dedication. What did it get her in the long run?
Will any of us ever forget the look on her face when she opens the door and sees Ennis and Jack kissing? This is something so foreign to her world, the shock is enough to keep her quiet about it. She never brought it up to Ennis through another eight years of marriage -- that's how foreign the idea of two men kissing was to her. She didn't know where to begin talking about what she had seen.
So, I think Alma is a sweet, innocent, hard-working, loving wife and mother who didn't deserve what she got.
(Don't get me wrwong. Ennis and Jack's love was all-powerful and all-consuming, but it did hurt Alma.)