How isolation happens so gradually, you don't notice 

There was a time when your life felt full. Or at least fuller than it does now.

You cannot quite point to the moment things changed. That is the nature of it. There was no single decision, no dramatic falling out, no clear before and after. Just a slow, almost imperceptible drawing in, like the tide going out so gradually you do not realise the beach has expanded until you are standing somewhere very different from where you began.