It's a classic way to end a story, but could have at least turned her back into an adult too. If editor is fine with the sex doll, then it's fine for both of them to do it too (after the confession).
Another yuri ended by the second volume... well, they will surely live together forever, getting lewder day by day. I must stress this, she is an unrivalled loli of culture.
The true story about the editor and sex doll was more fun that this manga, only chapter 1 was very good, late was a fall, Iroha was a great based character