If we have thoughts, questions, or issues about something, we dream about it to help us get more clarity. Too, sex is very physical, something our body is very interested in, libido having a lot to do with our overall energy, etc. If one is suppressing that, it has to come out in some way, we cannot truly "control" or emotional/thinking/body systems. Our bodies and "selves" have minds of their own and are doing their best to protect us, despite our own "personal" hang ups, handicaps, or brain-only decisions. Think of the "phantom limb" phenomenon, for example. Sounds like you are more-or-less engaging in a phantom sex phenomenon in trying to control that area of your life.