My heartfelt support to you, @secaries for reaching out to try to find out more about what is happening with your Grandfather. First and foremost, please remember that whatever is happening to your grandfather, it is his disease that is is causing him to change and not the Grandfather that you know to be kind, sweet and gentle. My husband is about your Grandfather's age and was diagnosed with dementia approximately three years ago. We have been challenged time and again with changes in his behavior - including anger, hallucinations, and, similarly, his belief that I planned to leave him to be with a friend of his. The path has been immensely confusing for me but always more so for my husband as he tries to navigate in his changing world -- I encourage you and your family to reach out and don't be shy about asking questions -- we've all had many experiences and I know that it helps me to be able to share and reflect on what has happened to my husband with others in this forum. There is much to understand and deal with -- it takes great energy and everyone here has provided me with good support as these changes have occurred in our lives. A specific question I would be asking with regard to your grandfather are the medications that he is taking and how effective they may be in helping him with his behaviors. For right now, we've finally identified a good mix for my husband but in the course of getting here there have been some meds and/or combinations that effected him poorly, causing hallucinations and/or not addressing some of the underlying issues. I welcome you to participate with us, freely ask questions and do wish you the very best with your grandfather.