Comment by ptrincr

There is an interesting answer here with regards to how the Pauli Exclusion principle is related to magnetism.

https://physics.stackexchange.com/a/246439

As I understand it, with my limited knowledge, deeper down it involves the exchange of virtual photons between electrons. I can see how this explains repulsion.

Though how this leads to attraction and how this looks as a Feynman diagram I'm not sure.