Morning Gordon
This actually could be the making of him
My eldest went to live with her father when she was 15 as she thought the grass would be greener (LO VERY L!!) and she was home within 3 months. She came home to a very different set of rules and whilst she did abode them for the most part, some times she strayed of the beaten track
Just to say really, that if (when) he comes back make sure you both sit down and talk about what you need to happen and what your son would like to see happening for life ot be lived in harmony.
Given you attitude as a dad I am sure you can make it work
Best of luck
From one parent to another