I have wondered if when her friends asked her if she was okay, as she was leaving C and C if they were detecting something. Like roofies. They pointedly asked her, said she said little but said she was okay. Some people on being given powerful sedatives, have a "look", sort of a stunned look. She may have had the drug given to her right before closing time.
But friends may have noticed something. That is my guess. And she may not have had the will or ability to say no. But Joran said she was "acting crazy". Maybe he wasn't lying, maybe she was, under the influence of something she didn't understnad.
I think Greta's whole point of the long story from the Croes man last night was that Joran had already concocted the lie, BEFORE anyone knew that Natalee was missing. In other words, HE knew she was missing, but no one else did, and since he has recanted this whole story that was recounted in the interview last night, he lied before he had to. Red Flag, Red Flag, and the little sob is going to get away with it, maybe even if they do find Natalee's body.