No, I'm not worried about losing my medfet or any of my other fetishes. If I lose interest in a certain fetish, it would stand to reason that I wouldn't care anymore since I'm no longer interested.
Like others on here have posted, I go through phases when I am more active on here, and more active with my medfet role play with my wife. Sometimes we get busy and we don't have as much time as we'd like to do the role playing. It is time consuming to set up the exam table and stirrups, get dressed in our respective role play clothing, perform an entire physical exam, then have sex after the exam is over. Not to mention cleaning up and putting everything away when we are finished.
Other times I've noticed that my medfet isn't as strong in my mind as at other times. Sometimes I think it's due to being tired if I've worked a lot of hours or had a lot of chores at home. I've also noticed that it is stronger during the winter, probably due to being cooped up indoors, since I HATE the cold and snow, and having more free time than during the warm weather.
Another time my medfet gets stronger is the time leading up to our conjoint physicals. In fact our conjoint physicals are in two months, so I have already noticed that I want to have more play exams, even though we've been busy lately. That urge to examine my wife and having her examine me will only get stronger, and the frequency of our play exams will increase, the closer the date of our real exams arrives.