My boyfriend's elderly cat, Tomas, did the staring bit for a year or two before he passed. He would also do some strange things, like going into the closet and meowing at my boyfriend's shoes! The vet never mentioned dementia, though now we know that is exactly what was happening. He lived to be 21-years-old, so I know we weren't cheated of any time with him. It was still sad, though. I would take Max to the vet. Maybe you can have couple more Christmases together. Hugs to you and Max!