Madonna originally wanted the kids with her in New York (presumably to be closer to A-Rod) and Guy wanted the kids with him in the UK. Since they couldn't come to a decision as to who gets the kids, they decide to be adults and give their kids one last Christmas with both parents.
An insider tells British newspaper The Mail On Sunday, "Madonna and Guy want the best for the kids and so she has decided to come over to the U.K. so they can be with their father. Madonna arrives in England on December 23 and is planning to stay for Christmas.
"Madonna doesn't really like Ashcombe but she thinks it's important that they put on a united front for the kids."
Guy apparently convinced Madonna into it because he hasn't seen the kids for weeks and wanted nothing more than to spend the holiday with them. And of course Madonna didn't want to spend the holiday without them, so they actually came to a compromise. Madonna and compromise usually don't go together in the same sentence, but there's a first time for everything.