A human dreams every half hour, but remembers few of those dreams and if we didn't dream scientists say that a human could go mad as it's the brain's way of releasing every day pressure. The dreams we remember are in the last moments before one comes out of REM sleep (deep sleep) and sometimes these dreams can be upsetting or feel like they really happened until one is fully awake. Just because you dream your wife is having an affair is not a sign she is. You may not be getting along; arguing or have problems in your sexual relationship. Instead of second guessing what you wife is up to it is very important that both of you learn to communicate (a tool in life you won't regret) and feel free to discuss anything that bothers the other without losing one's temper. Through good communication skills with your partner you can ease much tension and it is also helpful in resolving any issues in your marriage. You are probably worried that you are losing your wife to someone else if you have problems in your marriage or your sexual relationship isn't the best. Five senses come into play: sight; sounds; smell; taste and touch. You could have simply been worried; heard a friend or coworker talk about their wife having an affair behind their back; read an article in a magazine or remembered something you saw on TV. If you have been cheated on before in the past then something you see; a certain song; a certain smell or taste of food could certainly trigger this dream.