I remember the time many years ago when I read chapter 1-5 for the first time. It was such a wonderful feelings and I was hooked rightaway. BTW, the ending was a lil bit dissapointing. This epilogue is ok.
I think the next 2 or 3 chapters, Aya is going back to Haruki and use her as a replacement of Sei. She will hurt Haruki real bad and the circle keeps going.
Nobody will have a happy ending in the manga.
The ending will be that Sei is getting over Yoru. While Aya walk the same path as Sei and get stuck in her unrequited love for Sei. No one can help Aya even her friend. And Aya will do the same things as Sei does with other women./ End.