Cruise Crisis

Hi - this crisis has been stressing my family for over 2 weeks. I'd like an outsider's opinion. Here's the story, names changed, as briefly as I can tell it: Tom and Mary have been dating for almost 2 years. Tom invited Mary to go on a cruise. Tom asked his mother, Julia, if she would be available to babysit his dog. Julia agreed then told her daughter, Tom's sister, Ann, about the cruise. Ann had been planning to give mom a cruise for Christmas so booked herself and mom on the same cruise. When Tom told Mary, Mary was disappointed. Mary had been looking forward to a romantic cruise, and now mom and sister were coming along. Mary was at dinner with Julia and Ann. Ann asked Mary, "are you excited about the cruise?" Mary answered calmly, "it will be fun," her disappointment evidenced in her tone. Ann asked, "why do you say it like that?" Mary answered, "well, originally I had thought I was going on a romantic cruise. Now it will be a family excursion. But the more I've thought about it I think it will be fun for us all to be together." Ann was silent. Mary recognized that she had said the wrong thing and tried, unsuccessfully, to smooth it over. Ann, ultimately, rescheduled the cruise for her and her mother for another time, costing about $1,000 more. The final result is that Ann and Julia aren't speaking to Mary. Tom is hurt and betrayed by Mary's treatment of his mother and sister. And Tom and Mary's relationship is nearly destroyed. What, if anything, can be done to resolve this situation? Should Mary pay the $1,000 expense that Ann incurred? What apologies are needed?

Sorry why is Mary the bad guy here? Tom asks Mum to look after dog, sister books a cruise for a date Mum cant go on because Mum is looking after dog. Sounds to me like its all a big lack of communication. Is Ann single? Is she jealous of Mary or should she know better if she has a S.O.? Sounds like Tom should be smoothing the waters between his family and girlfriend. Does he want her to lie to his family or speak her mind? There is no betrayal mentioned here, if anything he should have said something to his family earlier not just disappoint his girlfriend and then blame her for being disappointed.