As for male input from a different perspective, I don't believe that your dreams are cheating in any way unless they stem from constant fantasizing while awake. I am speaking as the guilty party here. After I ended an affair 13 years ago, I still fantasized about the other woman even after we rebuilt our marriage and healed as much as was possible after what I had done. As our marriage has gone through some rough times of anger, bitterness, and resentment over the past few years, I found myself fantasizing about her even more. A few months ago, during a particularly bitter period, I sought out and reconnected with the other woman despite having not seen or heard from her in 13 years. A passionate affair ensued, with feelings even stronger than the first time. I moved out, we filed for divorce, and the other woman and I planned our lives and future together...until it all came crashing down. I now realize I was in a manic episode (my wife tried to warn me, but I wouldn't listen) and made major life changing decisions far too quickly and with too little thought for the consequences. I'm now sitting in the wreckage trying to rebuild my life and marriage, with no guarantee I will ever get either back.

So the short version is dreams aren't cheating, you have no control over them. If they carry over into waking fantasies, watch out and be very careful of your impulses and actions.