This exchange as well as others reminded me of American Gods, a novel that he wrote, where the main character talks to gods and mythical creatures with out realizing it at first.
This story actually surprised me because of all Gaiman books I have read from The Graveyard Book to The Ocean at the End of the Lane, none were so entrench in science fiction. Most of his work is based in fantasy, particularly urban fantasy. I guess the story is allegory on how hard its hard for some men to talk to girls. Enn, in the story, can only say a line or two to them and he sees them a beyond the standard of beauty. Even without the fact that girls are aliens looking to mate with him or worse, this may be a sign that he is seeing the party through stress vision, where his stress makes the situation look worse. You can also argue that this may an allegory for the fear of having sex for the first time. Enn and Vic are teenagers, they both are going through puberty and having sex is right around the corner. For some it is exciting, while for others it is a scary thought. Maybe the girls at at the party weren’t aliens, rather his anxious mind its morphing the party into something
worse.