My process in finding the solution
Guessed twice. First one accused green since I assumed she was part of the affair. Seeing both bathrooms and that she left from the bedroom made it suspicious that she went to the master bathroom rather than the closer one to the couch or dining table.
I might have also unconsciously picked up on the colors since the secretary had a chance of implying something. I thought it was more that green and red were partners, but discarded that when they didn’t seem to have interacted.
Second guess was a bit flimsy, but it was the correct one. Knowing what White AI said about not telling his wife (red) and her reaction being “I don’t know anything about that”. Was a little too standoffish, and combined with the choices showing Jealousy and Blackmail made it pretty likely that that was the answer.
The accusation menu might be a little too narrow with the Blackmail answer. Maybe if there wasn’t a accomplice motive selector?