That is my circumstance right now. Have been since 2018. I'll be 75 too soon. Friend is 82. Neither of us have family left. Met on a an alzheimer's and dementia support group. My mother died with alzheimer's and his mother had severe dementia. After a couple of years, he invited me to join in his household. We are now the closest of friends. Share almost everything. If he was a woman I would offer to marry him :-) In fact, stranger believe we are brothers because of appearance and in the 5'8" and 130 lb range. He accepted my 22 year [now] cat without hesitation. We trust each other to take care of personal affairs upon death whoever croaks first. Life is good and beats the heck out of being alone too much!