Did Lureen know that Jack was gay? Probably not at first, but over time.... yes she did. And, her father definitely did and disapproved of Jack. Look at the differences in the screenplay and the movie during the "Sit down you old sonuvabitch!" Thanksgiving dinner. Perhaps her father's disapproval of Jack is one of the reasons Lureen married Jack. In the movie, by the time we get to 1978 in the scene at the fundraiser for the Childress County Children's home, Lureen is clearly disappointed in her life. I think that she quietly accepted his "wanderings" as long as he didn't make a public spectacle of himself. Her tone when she was speaking with Ennis in 1983 after he learns of Jack's death shows that she had mentally compartmentalized Jack, and clearly he had not been the focus of her life for some time. On the other hand,for Alma, Ennis was the love of her life and she felt KEEN betrayal upon the understanding of her husband's affair with Jack. I don't think that Lureen ever felt for Jack what Alma felt for Ennis. So in Lureen, you didn't see the anger that was demonstrated in Alma....Lureen just had a sense that her marriage was probably a mistake and was dealing with it in the best way she could. I feel great sorrow for both women, especially Alma. The CLOSET has many victims, included in that number are spouses and children. Had Jack and Ennis felt free to live their lives together, two unhappy marriages could have been averted.