It's ok, but why even have all this drama to begin with when the solution was so braindead easy?
In terms of the narrative itself, Nazuna's plan was to wait until not only after Kou's candidacy ended, but after she stopped loving Kou, so that there'd be no danger of her
sucking his blood and risking either of their deaths. Kou couldn't come up with an alternative to that when she proposed it. Even now, he can only make the proposition he does (he becomes her boyfriend and wrangler) because he developed the means to in the time they were apart.
In general, I think Kotoyama might be a fan of putting boy characters through this "separation-and-reunion" sequence, seeing as she's done it twice (though, it has to be pointed out that the ending to Dagashi Kashi, contrary to popular opinion, is significantly different than this beyond the "separation-and-reunion" framework).
I mean. This reaaaaally feels like a "You have 2 months to wrap this up" type of thing, right?
No? Maybe Kotoyama was giving herself two months to wrap this up, but the announcement of when the manga would end was in the same year she won a big-deal award from
her own publisher. The kind of about-face that'd have to happen for them to decide to axe the manga would snap necks.