I think he did love Kay before Vito's shooting put him into the Family business. But when he returned to the US, I think she was basically a WASP ticket-punch for Michael--another ornament in his quest for "respectability." That scene in New Hampshire with him "wooing" Kay (Michael wearing that ridiculous Homburg hat, looking like a pint-sized banker) had all the passion of a real estate negotiation--with Kay as his property.
I am not sure about the “WASP ticket-punch” It seems the WASP is our doing!
j
As far as I can recall there was no such mention in the movie?