She still loves me but

We have been together since 2018. We love each other immensely. About a year ago, we moved in together, and I got a new doctor. He gave me anti-depression pills (I have been depressed most of my life). They left me with ED. Last April, we went on a camping trip, and I made a few mistakes in my driving. Now, I can't drive (we sold my car). I went to a neuropsychologist and he said I shouldn't drive, and I have a bit of dementia. Other doctors have said the same thing. She still loves me, calls me her fiance', but she talks about my dementia and won't marry me. I can not detect the dementia. I retired last year. What can I do? She moved out a month ago and bought a small house, which made me move out as well. We live close to each other, we are much in love, but she won't marry me.