Sara, don't stress about your dreams. I have been in a happy relationship for almost 9 years and still have "naughty" dreams about other boys. I search my feelings when I am awake to find any inkling that I have real feelings about these guys I dream about doing "naughty" things with, and I don't. Not a single real feeling whatsoever. It is really weird.
These are men who I would normally find either unattractive or not my type (the guy guy from uni who doesn't wash his hair, my married supervisor, my other married supervisor, my high school boyfriend who I haven't seen in 11 years...the list goes on). Yet I dream about doing rude things with them and in my dreams I am loving it!
Just enjoy the naughty dreams, I say - as DJW says, a girl has needs...even in her dreams!