ok well i don't remember what the specific trigger was for it, i think it's just random, so make a save and go to sleep at the camp, if it doesn't happen, reload and sleep again. Keep doing that until it occurs. Of course, if you don't care about the day count increasing just keep going to sleep regardless of having a save, if her affection is maxed and you've exhausted all conversation options it should proc eventually, i just don't know what the chances are, if you sleep 50 days and nothing then we've missed something. Bring that fact back to me and i'll explore things further. Hope it works out for you.