Sadly, it happens fairly often. Even the things that you love just seem to become less important. You don't make time for them anymore even if you still love them.
For example, reading. I used to read an entire book each day. It took me only a few hours to get through a book with 300 pages, sometimes more. I loved it. It was like you could have these fantastic adventures, feel the most painful heartbreaks, experience the best kind of joy, with out ever leaving the comfort of your home. And I just...grew out of it. Can you imagine that? I grew out of being an avid reader.