What makes one quit keeping fish? They find something even more interesting to do! And that is prone to changing as we each do change, even when we don't really think about it. I knew I had changed when I stopped playing with cap guns. I knew I had changed when getting married was far more interesting. I knew I had changed when grandkids became more interesting. I'm far more interested in an RV and it sure doesn't meet the plan to drag fish tank along!
I think it's called something like "maturing"? We grow, we change!