@Nanxing0 Yes, that is exactly how it should work under the normal circumstances that apply the vast majority of the time. And it would be really weird if we had to adjust our concept of how the duration of a stay worked around the possibility that guests might always be cutting it short halfway through.
But on the other hand, 1-and 2-night stays are a very easy thing to program our calendars against if they're causing too many weird experiences like this. Many hosts live in a place where they're important, like an airport suburb, but if this type of stay is something you can do without, you might consider setting a different minimum stay.
Although I see where you're coming from, I still think that it's responsible on the guest's part to cancel the reservation if they are finished with it and have no intention to return. Airbnb doesn't offer a simpler way of conveying that you no longer accept any responsibility for the property. I would be fighting in your corner if the guest left without notice but still demanded a refund, but I don't believe that the guest should need your permission to terminate the booking if they simply wished to leave and forfeit their payment.
Similarly, I don't believe that you should need the guest's permission to terminate their stay, if they have violated your rules and you no longer feel comfortable hosting them. In my opinion we are monetarily bound to the cancellation terms we agree on, but nobody should be forced to maintain an active reservation (and all the responsibility that entails) against their will.