I know we cannot turn back time, but unless this R was on solid ground and an actual R and a future was seen, you probably shouldn't have invited her on the cruise. I know you really wanted to bring a date this year. Trust me, I am the single one most of the time amongst couples, even on vacations. But putting in for a ticket for one probably would have been best for you and best for the organizers.
I agree with Andrew, keeping a woman around because you don't want to rock the boat (pun intended) for the cruise people, isn't really fair to her. You can't keep an R together for this reason. Find a buddy or another friend and I am sure being back-up on an all-expensive paid cruise isn't that bad of an insult. So please, do not drag this on for the sake of the cruise. Do what is right and fair for the both of you.
