Right but that's not the main difference. The main difference is that Reagan's remarriage occurred in 1952. He was elected President in 1980. So the event occurred some 28 years previous. So it was hardly a event in voter's minds.
Guiliani's is a recent messy divorce just a few years ago. And Guiliani has been married 3 times. So he has much more baggage to overcome than Reagan in this area ... plus he is not a Ronald Reagan.