Its a good ending for a manga that didn't really have much direction. Better than having a prolonged story with a bunch of unnecessary drama and love triangles.
It didn't get cancelled, the Mangaka was releasing the chapters for free on her own and then a publishing company approached her to combine them into volumes. So while I agree the ending is a bit abrupt, that was all the mangaka's choice.
Unfortunately, the mangaka has pivoted to character design for goods so they aren't writing stories anymore. But who knows? Maybe they will again in the future.