Sure enough, Nate, who seems to take his styling and behavior cues from Entourage and Axe commercials, tells Desiree that he thinks she's ready, but he doesn't want it to be with "the wrong dude." He apparently thinks Sean is "the wrong dude."
Nate asks Sean if he "can holla at you real fast." Desiree tells her parents he doesn't want Nate to scare Sean away, but without having seen the teased scenes, I'd be more likely to assume he just wanted to see if he could hook Sean up with some coke.
Outside, Nate tells Sean that it's clear Desiree's really into him, but he doesn't see any reciprocation. "What leads you to say that?" asks Sean, which, you know, isn't actually a refutation. "I'm crazy about your sister," he says. "You're crazy about a lot of girls, right?" says Nate, which is hilarious, since Sean says that to literally every woman and her family.
Sean is comically awkward about how great he and Desiree get along -- like Romney-level stiff as he talks about how affectionate they are with each other -- and asks if that puts Nate's mind at ease. It doesn't: "I think you're just a playboy. You're just having fun with the circumstances," says Nate. Sean is a lot angrier about it in interviews, but that's because he wanted to tell Nate off but didn't want to cause a scene here on a hometown date, which I suppose is fair. (The other reason is, of course, that Nate is a hundred percent correct.) Desiree, being some kind of professional empath, can tell something was up when her brother -- who already told her this is "the wrong dude" -- comes back in after talking to said wrong dude.
Lotta tension -- not defused by Desiree's parents making small talk about the weather. It's time to go, and Sean says he doesn't want Nate to affect his lack of feelings for Desiree. I mean feelings! His feelings for her! Sean and Desiree share a strained goodbye, and Desiree tells us she's really disappointed.
Inside, she asks Nate what he said, and Nate tells her about calling Sean a playboy. Desiree hotly says that's not what this is about at all. Her parents also think Nate is wrong, and it's really funny how not-seriously Nate takes this (which is, let's not forget, the only rational way to take it). "I can't believe you guys are drilling me right now," he says. "Because that's not what he's about at all!" Desiree tells him again. Defending your boyfriend against allegations of playboy-ism are admittedly difficult when he has been discussing love and marriage with three other women and their families ahead of you.