Maybe Chad complained about the set list.
More seriously
My 2 cents:
I think MK has never really found THE drummer, the ideal one, he sticks with the same band since 1995 but he has used 3 drummers already. And it was the same with dire straits. I wouldn't be surprised if Ianto was replaced at some point.
Interestingly when Jim Cox recovered from whatever it was that he had, MK immediatly took him back. If Chad did have a family problem, MK would probably have taken him back. As he didn't, we can assume it was either because Chad was not the best drummer for MK or simply because it was not a private problem to begin with but something to have with his behaviour in the band.
It's no mystery that Jim is the best piano player for MK. Who knows who's the best drummer for MK. I think he knows exactly what he wants in many areas except in the drum department.
It is also something I got to discover in my being in several (amateur) bands in the last 15 years (sorry for the drummers out there) but drummers are a special breed. They are usually very good musicians with a great understanding of music but they are also often hard to work with. It's like they have a secret lore and a will of their own when it comes to playing in a band.
Mk, who likes to rule all areas where music is concerned, needs a good drummer but also a good soldier, a man who will do as he's told.
So maybe yeah, Chad was fed up with Done with Bonaparte and So far away at the time! I'm only kidding!
I still do think Chad is better than Danny and Ianto.
This is only what I imagine, I'm probably wrong.