Wow I can relate to your post, my Father is 75, and hasn't had Alzheimers for very long that we know of, but this year has been a difficult one for him.
My Mother who is in excellent health takes very good care of him, she does get weary with the constant questions, and repeating herself over and over to him, but she loves him and really has great patience with my Dad.
My Dad has lost interest in most things he loved, he used to walk 4 miles every day, and now he doesn't, he loved to read and tinker in his shed, but not any longer, he sets around a lot looking lost and sad which breaks my heart. He constantly worries about my Mother, and she can barely get out of his sight, I know for certain he would never last in any Nursing home. We've discussed this and he will not go, we will take care of him no matter what, he is my Father and he took care of us, now it's our turn to take care of him. I know everyone doesn't have this option due to work, but my Father can't be away from his family he would just give up in a nursing home.
This illness breaks my heart, the person you once knew is not the same person, my Father was always such a strong man, a very hard worker, now he looks so frail. Just makes me incredibly sad.