Aniyome no Inketsu ~ Uragiri no Daishou

"You've got to pay the price for cheating on your spouse!"

You recently moved from the countryside to the city to attend college,
living rent-free with your elder brother and his wife.

One day you come home to what seemed like an empty house, but strange activity is
coming from your brother's marital bedroom. You secretly open the door to see...

[From DLsite English]