I definitely believe that Cousins wasn't happy about the amount of time IT had the ball, and prefers to play with a pass-first guy like Rondo.
And I definitely believe that Sac wanted to keep Cousins happy by going after the exact pass-first PG he wanted (Rondo).
Neither of those statements mean that Thomas/Cousins didn't get along on the court. I'm sure they got along great, just not as great as Rondo/Cousins.
I don't think it's that Cousins didn't/doesn't want to play with IT, I think it's just that Cousins wanted to use his power and get the 2 players he wanted in town. If you can do anything you want, and you want to play with your favorite PG, it doesn't matter if he's replacing your 2nd favorite PG or your least favorite. Just because he prefers Rondo, that doesn't mean IT is way down there on the list of PGs he'd play with.