At the "sit-down" between Michael and Fredo in Havana, after Michael reveals his uncovering of Roth's plot to Fredo, Fredo asks, Why didn't we spend time like this before?
I think that comment is a total ruse and ploy on Fredo's part, and by no means is it genuine remorse that the two haven't spent time together. He's afraid that Michael might already suspect his treachery, and is trying to save his own butt. What an asshole.
