My wife once asked if I knew what happened to my first serious girlfriend. I said no, we had completely lost contact.
Technically, we don't speak. But once every year or two, I search her name online. I know where she lives, what kind of work she does, and that she has children. I don't want to contact her or leave my marriage. It's more like checking what happened to a road I didn't take. Still, I know my wife would be hurt, so I keep it private.