I believe that Michael really did love Kay before the Sol/Mac shootings--there's a nice deleted scene of them cavorting playfully in a hotel room that shows real affection. But there's no doubt: Apollonia truly hit him with the "thunderbolt," and it was love at first sight. I think part of Michael's fall for Apollonia was his embrace of his Sicilian heritage after he became part of the family by rescuing Vito at the hospital and whacking Sol and Mac. The traditional Sicilian courtship and wedding shows it.

His wooing of Kay after he returned to the US struck me as cold and businesslike--as if he were adding another possession to his portfolio of "legitimacy." Kay's WASP credentials, values and manners were, to Michael, a certified sign of "legitimacy." (In the novel, Michael's disappointed that Kay took instructions in the Church and raised the kids as Catholics--he preferred them to be Protestants because it was more "American.") I believe he loved Kay in his way, but the loss of Apollonia withdrew a lot of his emotional capital.

This raises another question: In III, just before Calo tells him that Don Tomassino's dead, he begs Kay to "forgive" him. Do you think that was his only motivation? Or do you think he wanted Kay to remarry him to cement his "legitimacy"?