Andy's first main point in visiting Doug is to make the point that he is horrified that Doug called and got the Mermex deported. Doug says it was no more necessary than Andy screwing her, which does not make sense to Andy: "Yeah, but she's hot." Doug gets to do a funny little speech: "She wouldn't fuck me, but she fucked you? Well, fuck her. And fuck you!" Andy ignores this and points out that, even for Doug, bringing in INS was awful. (I thought it was completely typical, and in fact fell into that narrow marginal area of things Doug has ever done that I find awesome; c.f. the entire war with Celia and the Majestic Agrestic Community Police, and his relationship with Nancy for the first couple seasons.)
Doug turns it around in a very telling way -- telling both about Doug and about the way the people in this world work -- by responding that Andy broke a code by sleeping with "a friend's girl." So you did something terrible -- but that's okay, because somebody unrelated did an unrelated terrible thing. That's so Weeds. Andy points out that Doug has no room to talk, having boned Celia who is his friend's girl, technically, so Doug is the original codebreaker. And to Doug's credit, that's enough to shut him up. Andy cuts off Doug's Mermex whining by noting that he wasn't even really in love with her, but with a sad saggy-assed midlife cliché fantasy, and in fact he's still in love with his lesbian wife, so Doug totally flips the script on him; paints a portrait of him from the outside, noting the angle of the light and the trick of a smile that the subject of a portrait would never have the courage to see: "You're in love with Nancy."
Andy responds with a bewildering word salad, deaf to Doug's pointing out the elephant in the show, which is that nobody would put up with Nancy's bullshit for five seconds if she weren't Mary Louise Parker and everybody weren't in love with her. Andy weakly protests that he puts up with her shit because of the kids, and Judah, and Doug presses him. "I don't love Nancy okay shut up," he says, back on the playground, and then answers a call from Silas, who is going to need a new place to store his headcheese now that he's become Exhibit A in a nasty divorce. Doug begs him to stick around and smoke out, but he can't: "Shit's blowin' up!" Doug whines about how his shit used to blow up but now it just sits there. Andy agrees that this is tough shit, and the scene finally, finally ends with one more mumbled "shit" from Doug, toking away.