When my brother’s in-laws moved in with him and his wife, they were alarmed to discover that Mom’s short term memory amd focus had really declined. She started to fix her husband lunch, and was talking and moving around the kitchen doing this and that. An hour and a half later, there was still no lunch, and she was not remotely aware that so much time had passed. He was still hungry, needed to take medication with food, and had been sitting right in front of her the whole time.
The wife in this story may well think she is doing fine, and she really isn’t.
Like #9 said, it’s a tough situation. I’m wondering what my wife or I would do in a similar situation, by the time it happens, you don’t even know it.