To me, short stories can be really good -- but this is not one of them.
The switch between past and present destroyed the flow of relationship-built between Kelley and Simon to me as a reader, and I lost emotional connection to them. Suddenly years passed, and important things were mentioned as reference. Which is too bad since there were potential moments between the two, which clued me that they have chemistry and tender loving times as long as they have become friends
The sci-fi world is paper thin; it can easily be a present/contemporary situation. The plot is barely there.