I really don't understand all the furor over couples supplementing singles. They DON'T.
A room at a hotel costs the same whether one or two people are staying in it. Plus, OAT/GCL negotiates discounts far below published prices.
Usually, single cabins on the cruises DO have a supplement.
Then let's not foget the extras like the bar bill. One single gent on my last cruise has a bar bill in excess of $300. Then there are the optional excursions. Often priced way over what a traveler will pay doing the extra sighting on their own.
I assure you OAT/GCT has run the numbers every which way and they're not losing money or charging couples more.
However, the Good Will generated because the company is Solo friendly is worth millions.
I will be taking my 5th SOLO OAT/GCT adventure later in the year.