Even though it's a good ending it still feels like it got axed. If it was meant to be sex ed then there's still so much more for Kazoe-san to learn... They haven't even covered all the basics...
It's not precisely romantic as the ending I was thinking about, but it made the Manga feel like a coming of age sort of deal and it worked wonderfully. You can see that wall she put around her breaking and how they develop a friendship (and maybe something more)