"Isn't 'anxiety' usually used to cover unreasonable behaviour?"
@LadyRannaldini - I can't say this is something I have come across myself - I have anxiety myself (not self diagnosed - my psychologist's diagnosis), so I do know how it can affect normal life - and I know that I put on a show of coping, a lot of the time, only letting the mask fall with people I trust. But I also understand that, as there are few obvious signs of anxiety, people could use it as an excuse.
I can understand why Carol is feeling anxious about the trip - I will happily plan things, and then get massive cold feet nearer the time. But there is no way I would impose my dh on a girls' trip/holiday, to help me manage my anxieties - that is completely unfair.
And it's not as if Carol is going to have to do this trip alone, with no safety net - she is going to be with three people who are her friends - and I suspect that, if she could get past her 'I can't do it without dh' mindset, and got to the airport with the other three, she would find that the four of them had a great time, and that her worries were completely baseless.
It's not an exact comparison, but last weekend I went away on my own, to a knitting and crochet festival - Aberdeen Yarnfest. In the run up to the trip, I had lots of anxieties about how I'd cope on my own with the travelling, taxis to the class I was doing and to the hotel etc etc - but I pushed myself to do it, and it was great. It didn't all go entirely smoothly, and some of the things I was worried about did happen - but I coped. If Carol could get herself to the point of going, I bet she'd have a great time, and would come home with a real sense of achievement.
Which is not to say that the trip must become Carol's therapy - that would be selfish of her - I just think that it would be a good side effect of the trip. But the bottom line is that she cannot bring her dh along - it would completely change the trip, and that would not be fair on Anne, in particular, or on anyone else in the group.