This is a fanfiction story continuation of NTR ero manga "Boku wa Tsuma ga Netorare Nando mo Ikasareru Sugata o Mitsuzuketa" or "僕は妻が寝取られ何度もイかされる姿を見続けた" by sanku. I highly recommend to read the ero manga first before reading this (As I'm writing this it currently has 3 chapters, you can find the 3 english chapters on e hentai, nhentai only has 2 english)
The story was about a normal salaryman who have a very beautiful wife, one night when he was Infront of the door he heard a man's voice inside his house, he can't believe what he found out.