A confused mind

Mine not Bob's. The last few weeks have left me in a state of confusion. How Bob's Dementia can drastically change from day to day is not just confusing but leaves me wondering if it is me that is confused.
Yesterday Bob didnt have a perfect day by any means but he seemed what I call " the last stage normal'.. meaning as good as he could be at the stage he is at.
Today he could not put a coherent sentence together nor could he dress himself and he couldnt find his way around the house.. I could tell what he wanted most of the time-- he just couldnt take the steps needed to get from point A to point B..
Tonight we are sitting here in our chairs and Bob reached over and took my slippers and was trying to force them on his own feet over his own slippers.. I said Bob- those are my slippers- You already have yours on..
He said- "they are? "
Me- "Yes- Are your feet cold? Do you need a warmer pair of socks?"
He said- "NO-- I;ll just wear these" and kept trying to put my slippers on over his.
Sigh.....