I have ALWAYS found that point weird. In a big place (stadium, big bar, etc) my friends & I always go w/@ least one other girl just for the sake of having someone to talk to while you are in the never ending line. However, I have also been to concerts, bars, etc where I have met a girl sitting near me & we have ventured to the restroom together leaving my friends behind.
I do have a hard time figuring out how Morgan go outside the arena that night -- I believe the friends know how/why she got out there & as does LE. There is no way that the call/text discussion w/ the friend inside did not include that information. That would be the first question you would ask before you tried to figure out how to get her back in.