For me Michael sincerely loved Kay because yes was the opposite of the sicilian women that his father want Mike marry; Kay was blonde,indipendent and go to university.

I think that Michael loved more Apollonia and with her death the Michael feelings become to die; yes "love" Kay but the abortion would certainly killed her, if weren't for the sons.
I think that the feelings of michael are dead or dormant during the two movies.
When in Sicily in the third mvie Michael tries to regain Kay, he does so only because would remember the old days when they were young and happy.