When Derek joined her , the door man unhooked the rope to let them through , still watching Lucy with undisguised lust as they walked in . A look of utter confusion shown on Derek 's features as they were granted entrance into the club . He draped an arm over Lucy 's shoulders and they made their way through the crowds of people . " So how 'd you do that ?

Question: What may be the reason for Derek 's confusion ?
Answer: He did n't understand how they were able to get in so fast .He did n't understand why he was let in with her .He did n't understand why they were there .He did n't understand why he bothered coming .