Alzheimers and lost time

Some of you probably can relate to this. My husband has Alzheimer's. He was diagnosed 6 months ago but he is considered in the moderate stage.
I asked him "Honey, why are you constantly wanting to kiss me?" and he said, "I am so glad that you are back because you were gone for so many years."
We have been married for over 50 years and we have never been apart. This disease is very perplexing.