The embarrassment and confusion over making love to someone in your dreams other than your partner can be quite alarming and confusing. Especially for people who are in committed and loving relationships. It has happened to me, too! But here is the good news: It probably does not mean what you think.
Think about it. Dreams are usually symbolic. They are showing you one thing in terms of another; they are metaphors. Like poetry. They do not usually show you literally what they are trying to say. (But it sure would be nice if they did!!)
So if the lover in your dream is not actually representing himself or herself, who ARE they representing?
Many (if not most) times, other people in your dreams represent aspects of YOU, the dreamer, that you may not be consciously aware of. This holds true for dream lovers, too. Whenever dream lovers appear in a dream, I ask the dreamer to describe that person. In other words, to tell me what comes to mind when they think of this person. For example, if the lover was Elvis, you would probably think of music. Einstein, scientific intelligence. You get the idea. Then I explain that making love in a dream can represent "loving and connecting with". And what is it, then, that we are "loving and connecting with"? The qualities of the dream lover of course!
Back to our examples: Making love to Elvis in your dream would represent "connecting with your own musical abilities. With Einstein: Connecting with your own scientific intelligence.
I consider these types of dreams to be powerful in that they direct us to forgotten aspects of ourselves. They help us to regain parts of ourselves that we have left behind and they move us forward on our spiritual journey.
So, embrace that dream lover! He or she is a lovable person who has come with a message for you: Love yourself and move forward in a new awareness of who you are and your special gifts! Embrace YOU.