IOTL Henry VIII and his first wife, Catherine of Aragon, were unable to have a surviving son, which of course led Henry to want to divorce Catherine and remarry, and then to start the English reformation when the Pope wouldn't grant an annullment.
So, what if Catherine had had a son, and she and Henry stayed happily married until the end of their days? Would England still turn Protestant at some later point? If not, what kind of alliance would be most likely (England-France vs the Hapsburgs? England-Spain vs. France?)