Isn't it obvious? Ray left because he was insulted/offended/hurt by the trade rumors. I mean, that's pretty much exactly what the guy has said himself. He left because he didn't feel wanted.
The only other explanation, which I'm sure played a factor, was that he probably didn't want to come off the bench for Bradley (but as a professional, he would never publicly admit this).
Put those two things together and it's pretty clear what his motivations were for leaving.