An extremely awkward form of sex dream where the dream-partner in question is an ex-lover.
Unlike normal sex dreams involving your current partner, or a random friend/acquaintance, (s)ex dreams are disturbing because you KNOW what the sex with that person is like (and so the dream is more realistic), but have valid reasons why you are no longer with them.
General feelings upon waking include: feeling dirty and ashamed, horniness, guilt, nausea and confusion. These feelings are amplified if you found yourself enjoying the experience.
Even more awkward when you are in bed with your current partner and you have a (s)ex dream.
I had a (s)ex dream about my old girlfriend, Claire, but I woke up feeling really guilty because I was in bed with my wife.