AI kind of agree with what you originally thought, Turi, about Kay being the choice by default.

As I remember someone pointing out in a similar thread a while back, "What was Michael to do when he returned from Sicily? Start hitting the singles bars?"

There's always been an awful lot of "inter-marriage" within Italian organized crime families in real life. But somehow I just can't see Michael with, I don't know, someone like Rocco's daughter or something.

Had Michael gone "outside the box" looking for a wife, he would have had an awful lot of explaining to do about who he was and what he was all about to any potential girlfriend, much less future wife.

At least Kay already had an solid inkling about what Michael and his family was all about, and the explanation he gave her when they met after his return was very plausible because he believed it himself.

Kay was the logical choice for many reasons.