I didn't dislike Randall; as far as Ennis and Jack are concerned he's arguably an innocent bystander as he can't have any way of knowing in his one scene of Ennis' existence. And later.... well, from his perspective this is a relationship that obviously isn't doing Jack any good so I doubt his intentions are bad.
And Randall appears to be stuck in a marriage at least as bleak as Jack's, with a wife who clearly thinks she's married beneath her. While his wife's chatter sounds silly and innocuous on the surface, there are snide little put-downs scattered throughout, such as "like it or not, here I am!" (when someone says "like it or not" about their own situation; it's a bet that not is what they're thinking of). She makes a point of Randall not knowing what to do when the car breaks down and when she tells Lureen about how much money she spent on clothes while working for Neiman-Marcus, she mentions that she spent "more than Randall ever will make."
And as someone who attended college in the Deep South not far from the time that LaShawn and Lureen did, I can tell you that the Tri-Delt sorority (Delta-Delta-Delta) was the sorority for rich and semi-rich Daddy's girls at that particular time and place. IMO, her remark about Texas not being what they expected and her indirect reference to her income isn't unrelated to that. Jack might have been the best thing Randall's eyes had seen for years!
Dont forget Lureens dig at Jack, "Husbands...dont never seem to want to dance with their wives. Whyd you think is, Jack." and his brush-off, "Never gave it any thought." Both women are putting on a show but there is clearly anger underneath at there men who are not being husbands to them, the fatigue of being married to a closeted man and wondering why if youre holding up youre end, the men aint behaving like the marital-advice books say they will. They are both good-looking women, havent let themselves go, dont keep a funky house, so what gives, they wonder. Theire men no doubt do there share of drinking, how couples in their position coped in those days.
Randall is maybe a year or two older than Jack, maybe they been married a little longer (you dont find out if theres a Randall Jr. but I assume theres kids), long enough hes learned to do that male eye-dance you can back away from if your radar turns out to be off.
I got a hard time watching it too, but because I lived it, and I know too well what comes later, when the couples part ways and drive home in silence to their resentment and obligation-filled homes. That kind of silence between man and wife can lie so thick on the dark bedroom it seems only a gunshot can break it.