The person on the other side of the door claims to be room service, which makes Seth even more confused, since neither he nor Arabelle ordered room service. But the mystery gets cleared up soon enough, when the person at the door is revealed to be none other than Seth's wife, Pily Visual.
Seth thinks he's in big trouble, but Arabelle explains that she and Pily have actually met before, so they set this whole thing up. Pily is fine with Seth having sex with Arabelle... as long as she gets to watch. Seth asks if this is a trick, but Arabelle and Pily assure him that it's not a trick, other than the room service stunt of course. Seth is stunned but grateful, and eagerly has sex with Arabelle while Pily observes the steamy action.