Michael is wearing his wedding ring in the notably older Michael scene, in Godfather 2 so either Michael is in denial that “Kay was gone†or Michael and Kay had not divorced
It's a good point. One thing to consider in connection with denial is Michael's Catholicism. A Nevada divorce wouldn't have any impact on the marriage's status in the Church. So Kay could be divorced at the same time Michael considers himself married, or at least projects that does.
