I believe Michael really loved Kay at the beginning--before Vito was shot. You see him actually being playful with Kay in their hotel room in a deleted scene. But, after he killed Sol and Mac, and Sicily, and Apollonia was killed, Michael was a changed man. There's no romance in the scene where he woos Kay in New Hampshire--it was a business negotiation, Kay was another step in his obsessive quest for "legitimacy"--a WASP wife to bear his children and bolster his "legitimate" front. Whatever remaining feelings he had for Kay were subordinate to his selfish personal plans.
Sure thing Turnbull we could see the changes occurring in Michael among others, from the moment Michael reading about Vito's murder attempt in the Newspaper, his dinner with Kay in the hotel just before Michael visited Vito at the hospital and the subsequent sequence of events
Michael seemed to sense he cannot continue to distance himself “That's my family, It's not me” and needed to step up
It seems the WASP is our doing! As far as I can recall there was no such mention in the movie?
Besides WASP Kay was
already Michael's girlfriend, long before Michael having to become the Don and the quest for "legitimacy"
