https://www.dlsite.com/books/fsr/=/title_id/TITLE00200770/order/title_d/from/work.titles
As always, please support the artist and buy his works.

"Contract Wife - Days of Being Embraced by My Husband's Boss, It Started for My Husband's Sake"

The middle-aged man's sticky tongue enters her pussy. Despite her disgust, her pussy begins to overflow with a slippery liquid...
Saeko is now working as a domestic helper at her husband's boss Tasaki's house. Saeko falls into Tasaki's sneaky trap and is forced to act as his wife while at home, becoming his "contract wife". While Saeko is forced to clean the house on all fours with a naked apron, Tasaki fucks her deep inside. He plays with her plump breasts while thrusting hard from the back.
After rubbing inside Saeko again and again, Tasaki says, "We're a married couple, so what do you care?" and unleashes his own lustful liquid...

Funnily enough, I bought this one more or less by mistake. I mistook it for this one (https://www.dlsite.com/books/fsr/=/title_id/TITLE00271731/order/title_d/from/work.titles), another work from the same author that deals with married women having sex with their husband's boss, but one where the husband's boss in question isn't a DILF, but rather a younger guy more or less in the same age as her husband.

Anyway, I figured since I had already bought this one I better publish it for you guys to view. And don't worry, I already got the other work that I really wanted in the first place and will post it sometime later.

This author is severely underrated. His work is excellent, both in art and plot. Someone should comission a translation for one of his works.
If anyone can recommend a good and safe place to comission a translation, perhaps I myself will in the future.