Tanshin Furin -Netoraretara Netorikaesu Baigaeshi-

The male protagonist, a programmer working at an IT company, was sent to another city for an outsourcing project.
There, he met the female protagonist, who was assigned to work with him on the same project.

One day, she approached him to discuss something.
It turned out she suspected her husband, who was working in a different city, of having an affair.
On her husband’s social media, she’d seen photos that included items belonging to the male protagonist’s wife.
When the male protagonist returned home, he checked his security camera footage and, sure enough, saw the female protagonist’s husband there…
After confirming he’d been cheated on, the male protagonist decided to get back at him by seducing the female protagonist as revenge.

Translated from dlsite