The things that you thought to be permanent were the ones that ended up being part of your past. One thing is for sure: you can't tell whether the things that seem very perfect, lasting, and happy would be forever. They usually wear off at some point. Don't ask why, though, just try to understand how it came to be. Such thing happens and it's normal although it hurts.
We grow. And sometimes growing up means breaking away from a good habit. It really is difficult at first but you know you need to walk away to open up new adventures. The reasons may be difficult to understand but you know deep inside that you need to break away and move along and make new experiences, fresh experiences. These reasons, though blur, will find its way to you and slowly explain why.
I'm on the next thing; along my journey, it excites me to know what is there and what isn't there.