He realised what was going on when the salesman called her the next day. They discussed the initial day Joe wanted the couch to be delivered. It was again this exciting chat among two people who desire each other that turned Joe on. When his wife told him that there would be a problem to deliver the sofa on a weekend Joe was not surprised. He knew that all this was bullshit. His wife and the salesman wanted to deliver the couch when Joe was not at home.
Now Joe knew what would happen. Normally the sales guy would not deliver furnitures himself. He was a sales, but for this order he would bring the couch personally. After the couch was placed in his living room the sales guy would ask his colleagues who carried the couch to leave. He would lie to them and tell them an excuse why he would need to stay a bit longer. As soon they were alone they would sit down on the new sofa and talk. Just for a few minutes before they would start getting closer to each other.
Joe was not jealous, but excited. He masturbated on his phantasies how the salesman fucked his wife on the new couch. He would not come on that day to watch them through the window or to caught them in the act. Instead he would just enjoy the excitement of the relationship. When his wife would mention the couch and the sales guy he would talk positively about him and tell his wife what a nice guy he was and how cool it was that they saved the money. This would strengthen his wife in her affair with the furniture guy and instead of being more careful to cover the affair, she would let Joe knew more about it.
One day she might trust him so much thatch would tell him everything or let him even watch them.