He gestures vaguely with a wave of his hand before he answers, "You are more than welcome to ask him. Cole is a friend of yours, I assume."

Solas has traveled with Cole long enough to know that any answer he gives would have to be deciphered. Either way, his reasons for leaving would hardly matter to someone from somewhere other than Thedas. His reasons for keeping them to himself are entirely centered around him being a private person.

That and he enjoys being a pain sometimes.