I get these kinds of stories almost necessitate a timeskip ending, but come on. First she goes three months without telling them about it; did they hang out at all during this time, and she just never felt like bringing it up, or did they just never run into one another? Then when she tells them, a week before she leaves, her reply to the girl she likes telling her "we won't be able to see each other anymore... I'm going to miss you" isn't "we can video chat, a technology that was shown to exist ten chapters ago" or "we can keep in touch on LIME, like we've been doing from the start", it's to tell her it's only going to be three years, because three years is such a short amount of time for a child. Moreover, a three year timeskip is to when Koharu is in middle school; I was under the impression that age gap series had timeskip endings so that the relationship could start or continue at a period where it's socially acceptable, but I guess they're just for their own sake.
I like this series, I'm going to reread it, I get that it was probably axed, I get that it isn't the worst timeskip ending ever, but still.