Under those conditions I can see how it would be awkward to let the amnesiac know about your relationship.... though I was somewhat hoping that the amnesiac would either upon her entering leap from the bed and perform a kabedon while asking who the pretty lady was or that some lewd hand holding would restore her memory.
>a reset only lets Nanako fall in love with Rin all over again
>Rin gives up her resistance and tells Nanako to call her Rin from the outset instead of when the moment of passion inevitably comes again
There's just no winning.
Going into these one shots is like pulling in a gacha game; you never know if you're gonna win big, or end up with something shitty. In this case, I didn't have time to see what I got before I was sucker-punched in the face.