Mom thinks Dad is going to put her away and move a girlfriend into the house.This has gone on for over a year. I don't know how to help.

She has been diagnosed as being in the early stages of dementia (most likely vascular), but insists her memory issues are just old age. She says that neighbors call to tell her that they've seen Dad taking this girlfriend for rides. (I've spoken with these neighbors. They have not.) Dad DOES NOT have a girlfriend. Dad is her sole caregiver -- dresses her, makes the food, and handles everything at home. She knows how dependent she is on him and I'm sure this delusion comes from the fear of overloading him or losing him; the guilt and other feelings. She is frightened and sad and I just don't know how to help. I've tried to address the emotional component and then distract her, but that no longer works. She is still on the ball enough to recognize the attempts at distraction.