Yes, but that can be said for any marriage before end up getting divorced. You do make plans. You do plan to live somewhere, you don't plan for divorce. (Although celebrities probably should).The thing is, Joe has knowingly agreed to moving to the UK and planned a whole future for them there.
The plans they had for the kids have to be changed now. They now need to work out an agreement that is beneficial for the children and living full-time in the UK or living full-time in the US may not work. It needs to be what's best for the children and for the parents to have equal time. Just because he agreed to it when married doesn't mean now with getting divorced he has to stick with that.
And if the UK was end all and be all for everything, why were the children with Joe in the US for all this time on tour while Sophie was working in the UK? Wouldn't they have been in their school or dentist appointments or whatever with a nanny or her fam?