I’m not aware of any cruise line that runs its own singles cruises. Most singles cruises I’ve heard or read about have been whole ship charters put together by special interest groups, associations, clubs, etc. On the other hand some cruise lines are more singles friendly than others. By that I mean that some have better, like in lower, single supplements, organize and run on board singles events (i.e., dinners, tours, cocktail parties), and in general reach out to singles.