They hustle into the car and take off. Where are the friends who came with her? I guess they had different flights. They pull into the airport at 6:01 AM. In an interview, Nathan says that if they hadn't been drinking, they would have been up on time and had plenty of time to say goodbye at the airport. He didn't get to hug her and tell her how much he loves her. Or that he cheated on her. Nathan runs into the airport, but I guess her flight boarded already, because suddenly he's back at the car. He voice-overs that he's drinking a lot, and that it might have ruined his relationship with Stephanie.
Back at the house, Nathan sits in the car, and probably cries. You can't see his face, but at this point, can't we just assume? He voice-overs that he doesn't know what's going to happen when he goes home, which is "the worst feeling [he's] ever had." In an interview, Nathan (surprise!) cries and says that, in the past few weeks, he's imagined a future without Stephanie, and he doesn't like the way it feels. Man, either he's putting on a bravura performance, or he really loves her. Loved her. Nathan sits on the bed in the dark and puts his head in his hands.
Guess what? In the next episode, they leave the house!