William, it was really nothing.

So, he left.
He's set himself on fire,
burning those bridges so that
no-one can follow him.
It's like Jumanji, but a bit more
Hoxton Square.
(Can you fight crocodiles in a Tweed?)
So, he's gone.
...because to him it was the only way of saving his ability to love again, to stop him looking like a ghost, to get colour back, to respect.