That's a really interesting question, Don Alfonso.
I've always felt that his memory of Pop's birthday is really poignant.
Look at the people in that scene: Michael has had three of them killed. Another was murdered by the Family's enemies. Connie and Tom are still around but haven't exactly had close relationships with Michael.
Michael might be regretting how things turned out. Or lamenting what could have been. But maybe not.
I would use the word "bewilderment." Who's the smartest guy in the room? He is. What decisions would he change? None. So why is he sitting there all by himself?
It's striking to me that he's sitting alone at the end of BOTH scenes. I think he may be reflecting on how not much has changed, regardless of whether he was surrounded by family in New York or isolated in the "Sierra mountains."
He's a much different man in GFIII. I wonder if that scene's realization - that he's always been a man apart - was the root of his attempted transformation.
