We all can complain, but in fact, I liked the open ending. We know that Kokonotsu will still be having his third year with his friends and gather a lot of stories and memories along the way. He likes Hotaru, and it is implied that she likes him in her own way, but as a self-centered person, she will still follow her dreams even if he is not there. We won't see Kokonotsu rejecting Saya, but we know that they will never be more than good childhood friends, still, they are family in some way.
I can see Kokonotsu getting his space as a new-comer manga artist with a short series just like this one. Hotaru will work with her father for some years while scheming how and when to open her company. Saya and Tou will keep the cafe business in the town for a while and maybe join with Kokonotsu and Hotaru in the near future. It was a good ending for me. Being open-ended as it turned out to be, I can make a happy ending out of it. Just sad that I had to read the raws for chapter 156-181 (didn't understand much since I know almost to nothing of Japanese).