Lol, the ending fixed the story. The author probably noticed they ended up focusing too much on Shou and left Souko undeveloped, so they probaly made that ending to break out of the estabilished ending.
Great story, terrible out of nowhere ending that completely slams the door in the face of the reader, in my opinion. A solid 7/10 that could have been an 8 or 9 with a better ending. Your preferences/mileage may vary.