DreamsMaster: There are a few ways this dream can be interpreted.
1) It’s possible your inner detective (your intuition) is picking up clues that your wife is emotionally distancing herself from you and this marriage, and this intuition is playing out in your dreams as her cheating on you.
2) It’s also possible that in the back of your mind you’ve been picking up signs of her having an actual affair, and your dreaming mind is bringing it to the forefront to get you past your denial.
3) Another possibility is that the dream is not about your wife’s feelings or actions, but instead represents your own insecurity or lack of confidence and sense of control within this relationship.
Check out other dreams about Cheating in the dreams.com library, and see if there are more clues here for you.