Why did Pangaea separate?

Currents in the Earth's mantle broke it up and dragged it apart. Rodinia, Gondwana, Pangaea. The Wilson cycle completes on a half billion year cycle (about every 500 million years).

The movements of plate tectonics. When the plates move, the ground of Pangaea cracked and splitted up into Laurasia and Gondwanaland, which then split up into the seven continents that exists today.

We believe Pangaea broke up through the theory of continental drift. This is plate tectonics.
Plate Tectonics. The plates are floating and are constantly moving, according to the plate tectonics theory.