I read it a long time ago, all that i can remember is that there is a couple, dont remember if it is a married one or just a boyfriend/girlfriend relationship. if i remember correctly, they recently moved to that apartment or at least, that is what i assumed.
I think that the neighbor's room was wall to wall because the couple could hear everything when the neighbor was fucking, but what a remember is that the girl decided to go to talk to the neighbor to complaint about the noise or something like that, but instead of it, she get fucked. I dont remember if she was frustrated but in the end i believe that she liked it.
Anyway, put the link :P
And thx for the effort.