> Another way of looking at it is that long-term relationships with prostitutes would fit your description.
There's not much data on that but I remember vividly reading an academic study that interviewed many prostitutes and cases where regular "clients" used their services for more than 2 decades while racking several divorces in that time where common.
I was really surprised at the time.
Maybe friends disappearing (like the article states) leads those men (in that study it was only male "clients") to pay to have a permanent human element in their lives.
You'd be surprised, but the qualifier "romantic" messes up with clearly addressing this (since it presupposes sexuality).
Marriage in most cultures have been more about the economic and companionship part than about sexuality up until recently. Heck, marriages were mostly arranged in most cultures until the last 1-2 centuries...
After all you can "play" around without getting married too, no need to marry for that.