DEAR ABBY: An old friend, a sweet elderly woman who lives in California (I live in New York), is suffering from some form of dementia. We keep in touch with phone calls. She lives alone. Our phone calls are important to her and to me, but our conversations, more and more often, are becoming endless, repetitive loops. The duration of a call is usually 45 minutes to an hour. However, now that every few minutes there’s a total reset of what we discuss, my friend seems to think I’m ending the phone call after just a couple of minutes. She doesn’t remember we’ve been saying the same things over and…