So, I know that the Protestant Reformation has its heart in the northern half of Europe, what with Martin Luther and Henry VIII and the cultural differences between the two halves of Western Christendom. And I know that the Papacy's main base being in the southern half of Europe and its distance from the northern part makes this difficult.
But I was wondering what it would take for Britain and the northern Germans to remain loyal to the Pope while Spain and Italy start a schism in the Church. And what such a thing would mean for Europe as a whole.
Interesting.
Keeping Britain and Northern Germany Catholic in an alt-Reformation is conceivable. I´m currently exploring something along these lines in the Hussite Reformation timeline which you can find in my signature. A Reformation, for example, which has a strong Slavic proto-nationalist and anti-German twist to it, won`t appeal to Germans.
The problem with your challenge is the other thing: making Italy and Spain *Protestant and still have Northern Germany being Catholic. If Italy goes *Protestant, what does it mean for England to be Roman Catholic?
The Pope can flee, of course... but that alone alters the character of Catholicism, as the period of the Avignonese Papacy and the ensuing Western Schism has shown.
Also, Spain has next to no tradition of Reformatory movements or even widespread heresies throughout the Middle Ages.
Italy did have quite a few heretic groupings, but the differences between advocates of Apostolic Poverty and enraged populists like Savonarola is huge and difficult to bridge. Italy`s Reformatory movement would require a very solid popular support in order to chase the Pope away, which it never came close to mobilising. Foreign interferences are of course possible, but off the top of my hat I can`t think of any which would truly be conducive to the OP´s end.
So - sorry, I´ve failed.
Is there some background which made you shape the challenge exactly the way you did?