OK guys, so before I start this, again:
I DO NOT SHIP FINNAME! I AM SIMPLY DESCRIBING A LOGICAL SCENARIO BECAUSE, EVEN IF I DON'T CONDONE, DOESN'T MEAN I WON'T DEFEND IT AGAINST STUPIDITY. NOW PLEASE READ:
So, a very common argument of why Finn and FP won't stay together is:
"If Finn and FP kiss, the world will explode"
Very valid argument. Makes sense and is true. But have you ever thought about something: If Finn and FP were to break up, FP refuses to go back to the fire kingdom and will find some other dude who has no idea about her elemental matrix and they will blow up the world, because they don't have Jake or Finn there to save them. We don't know deep detail about FP's condition. If her personality were to change to good and there were "penalties to her experience if she steps out of alignment" there is perhaps a way to fix her condition. Finn and PB are possibly the only people who can fix this, and without Finn, neither of them can help. She may very well find an evil guy who won't change her to good and she will blow up the world. Stop using illogical arguments and stop arguing about ships altogether.