Well, if you wanna know the full plot-twist thing to make sure I actually didn't steal from you, the couple mentioned in the beginning aren't actually the main characters of the story even though they end up doing the same thing.
Also, the Earth split apart because of an Earth goddess. And because of the main characters finding each other in the Ever Woods, the goddess realized it wasn't enough to split the Earth in half, she had to destroy it. But the main characters stop her from doing that with ✨the power of love✨