get your mind out of the gutter
Half way between the gutter and the sky...
I think that's the title of a Fatboy Slim album.
Don't get me wrong, I've got my morals as well. But I figured I would start the senario after Shinji fell on her, and how I would react to that. Assuming that I had actually gone in.
If it was actually me instead of Shinji from the start, then I probably would have cleaned the mail slot to put assignments in (yes, I would return the mail, no I wouldn't read it). After discovering the door was wide open, I would have left the assignments at the entrace and then left before she even saw me...
Hopefully, cleaning out her mail slot wouldn't take that long. If it did, though, I would nervously explain my actions and then leave. If she invited me in, hey, whatever. But if not, I probably would have asked for a drink, or something before I walked home.