Based on the erotic game by Orcsoft. 
 
I get the feeling that my wife has gotten more beautiful as of late. It's a small thorn that's stuck in my side and just won't go away. Niggling at my conscious that something may not be quite right. 
 
After much deliberation, I hire a private detective to investigate my wife's activities and I regret having ever thought of doing so... 
You see, having learned of your wife's adulterous affair with another man turned you on, made you burn bright with lust... like a horny beast. 
You wish you never learnt this feeling but... at the same time you wonder how you could have ever been satisfied without it... 
 
NTR... A forbidden delicacy. The dark swirling lust within you beckons... to draw you into a deep abyss, a never ending fall into cuckold depravity. 
Enjoy... as your wife moans and groans in the throes of pleasure... 
... with another man. 
 
(Source: DLsite English)