what do you think of cohabitation among old people?

I say "whatever makes them happy" :) my uncle and his cohabitator carolyn have been living together for as long as i can remember. He was happily married for years then his wife passed away. I don't know the story of how him and carolyn got together, they've been together for as long as i can remember. I don't think they should have to be married to live together. they've already done it once and some don't want to do it again.