I have two sons , one is 12 and the other 8 years old, they didn't adapt very well to the UK. The older has Aspergers syndrome and ADHD and he was struggling, in the UK despite the NHS being free there's little effort to help people with mental disorders. Schools don't really care about it either, so three years ago me and my wife made the decision to send them home and we started preparing things to come too. This summer we just decided it was enough, we couldn't stay away from them anymore and they didn't want to go back, so we prepared everything to return home for Xmas for good.
In Portugal despite what many people here may think the health service is good, and my son has had all the help he could to manage his ADHD and aspergers, on top of that the schools have given him the support he needed, at 9 he couldn't read or write a word, with proper support here in Portugal he is top of its class and has not failed a single year, and in the first year he had to work harder because he had to play catch up to everybody else.
So basically my sons were the main reason, second was that I missed home. Portugal is a good country to live, its relatively quiet and peaceful and I wanted to go away from the hectic life of London, there's no life and work balance there. You're either working or stuck on traffic and there's just too much stress. I just wanted a quieter for me. My hometown in Portugal is smaller than my neighbourhood in London, so it puts things into perspective.