In my opinion their relationship is already mended by the time the movie begins. In his letter we hear him reciting to his children at the opening, he mentions that their schooling had been managed by their mother. Also, Kay is a guest at the reception following his being honored by the church. They somewhat reasonably discuss their concern for lives & futures of their children. Far different attitude from the 15-20 years earlier when Michael didn't even want to see her face. They are no longer in love, but have already reconciled.

And of COURSE Kay blames Michael for Mary's death, and rightfully so...don't you see that look she gives him?

But of course...all of this stuff, including Michael's 'It wasn't me, Kay...' speech...was manufactured specifically to ensure Diane Keaton a prominent role in the movie. For it to even remotely succeed, they had to have as many of the original cast present as possible.

Oh, if only they had given Duvall the salary he wanted!!! But I digress...

Apple