Netorare Ren'ai Jijou ~Joushi ni Karametorareta Otomegokoro~

The story follows Sanada Akito and Seto Futaba, a couple working in the general affairs department of a small company. They handle various tasks and enjoy plenty of free time in their routine. Amidst a recession, the company celebrates a successful sales project with a congratulatory party.
Futaba, tasked with arranging the party venue with her boss Shimada Souichirou, goes on a restaurant tour where she ends up getting drunk due to Souichirou's encouragement. He takes advantage of Futaba's intoxicated state and they become involved in a physical relationship, leading her into an affair with him.

[Translated from Getchu]