This second episode has left me with very mixed feelings. OK, so maybe the incest angle was forced on the writer, but it was the pivotal point that gave a good, solid shape to the story. There are some less satisfactory aspects, though. For example, wouldn't any normal person regard chloroforming and kidnapping your ex as a completely unacceptable way to rekindle the relationship?
And what about the ending itself? Wouldn't two girls brought up in modern society go insane after a few weeks of living in a "paradise"? There's only so many times a day you can have sex before things get bruised and sore
And what about food and medical care? Oh well, I suppose that if we can believe that Kiiko's powers have become so god-like that she can teleport herself and Aaya across the universe then maybe they really can be together for ever. I hope so, anyway.
[Edit] Having re-watched the first episode, I can see the foreshadowing now:
"The school during summer vacation is somehow... otherworldly."
"The empty campus in the morning seems almost like our own private realm."
So perhaps an alternative explanation of the ending is that it's just a metaphor, and they went back home to resume their lives together.