Tsuma no Biniku o Masaguru Chichi no Futoi Yubi ~Shiranu Ma ni Chichi no Mono ni Natteita Tsuma wa, Yorokobi no Aegi to Tomoni Koshi o Uneraseteita~

After I got married to my wife, my mother was diagnosed with terminal cancer and died one year later after being hospitalized. My father became depressed and lost his will to live, so I couldn't leave him alone and we ended up living together.
Meanwhile, I was promoted, and my father celebrated with me, getting drunk in the process. On the other hand, my wife, who rarely drinks, got tipsy and started to act affectionate towards me. Despite my father being nearby, we ended up having sex in the heat of the moment...
However, drinking turned out to be a bad idea. My father continued to try to have fun with alcohol, but he couldn't get in the same mood as he did during the celebration and seemed to fall into depression again. Then one day it was decided that I would go on a week-long business trip...