Responses
I like this kind of requests ^^
here : http://www.mangago.me/read-manga/kocchi_muite_ai/
If you like drama, try this one http://www.mangago.me/read-manga/how_much_i_like_you/
it's exactly because the walls are too thin and the neighbor can hear everything at night that lead to the main pair's predicament（￣へ￣）. The problems only start to manifest around ch 15 or so, so you need to be patient reading it, but the story is quite good.
Looking for Yaoi that the couple either can be heard by friends or neighbors due to thin walls, to loud, etc. (≧∀≦)