In advanced stages of this disease, you really do lose the person you love. In my final few visits seeing him this year, he was physically there but mentally he was gone. Growing up, my grandpa was strong, wise and humorous. In his final few months, he could barely mumble a few words.
This is Life: birth and death. Great pain and great Joy, and everything in between. Experiences that shatter your heart but experiences that lovingly glue it back together again.