If you dream that you are being unfaithful to your partner means that you are having thoughts of being by yourself or have a crush on the person who you were unfaithful with. The dream shows that you are not happy the relationships you are in, at least this time of your life. If your partner is being unfaithful to you in your dream, it means that you are afraid of being betrayed or you do not trust this person as much as you would like to. Sometime we dream about our partners being unfaithful, because we are jealous while they are communicating with other people or simply doesnt pay as much attention as we would like to receive. The unfaithfulness is very common dream, so you should consider the relationships you are in and why you have these kind of dreams.
Read more about dreaming of Unfaithful in other dream meanings interpretations.