It is a Charlie/Joey story but Ruby and Nicole are a secret couple at the start as well. I've been looking for it for ages and trying to remember more about it but I can't remember. I just know it was really good.
It was also quite long. I think I remember at least 10 chapters and they had a lot per chapter.
I also remember one of the scenes: Ruby and Nicole were together in the caravan getting it on ;) and Geoff comes knocking on the door looking for Ruby and ruining there time together. ( He doesn't know about them - no one does)
I know its not much to go on but if anyone knows what it is please let me know.