Just to clarify, when we think about the Texan characters in the movie, we have to consider the screenwriters, Larry McMurtry and Diana Ossana, who are longtime commenters on what it means to be Texan. Think of Last Picture Show, Lonesome Dove, and Terms of Endearment, all stories about Texans. And in all those stories appeared enigmatic women, women shaped by their environment and sometimes driven half-mad by the experiences they endured. Why on earth did Emma marry Flap Horton in Terms of Endearment, and why was Aurora Greenaway so overbearing? It's never spelled out in the story, but the implication is that Texas is not the kind of place to have sensitive feelings or "tender mercies." Thus, Lureen emerges as the same kind of enigmatic woman. McMurtry never spelled out her motives and we could go round and round trying to figure them out. It's clear that she pursued Jack, maybe for straightforward reasons and maybe for devious reasons.