I'm sorry to say this Crycket, but your friend sounds incredibly selfish and self-centered to me. I understand that some of that has to do with the illness she's been enduring, but to expect people to A) use their vacation time and dollars for this wedding, B) be stuck on a cruise with a bunch of other people while the newlyweds indulge in each other, and C) accuse other people of not caring and of being selfish when her demands are unreasonable is going beyond the pale of what is acceptable for friends.
I would not want to accompany any couple on their honeymoon, especially if I had any sort of phobia about that sort of thing and her insisting, knowing this, is unreasonable.
Send a gift and let it go. She's the one who is not being "friendly".
Knitting to keep my sanity. It's working... kinda...
OTN: Dr Watson's Cable Crew Neck
OTN: Writer's Cardigan