[sd79812]

The bar magnet=electron analogy doesn't work.

If you put different polarity bar magnets adjacent to each other, the magnetic field lines don't disappear.

[Borek]

Depends on how far you are from the magnets/electrons. Sure, if you are close, you can easily detect the field, but it gets weaker very quickly with the distance. Much faster in the case of two magnets/paired electrons than in the case of a single /unpaired.

This is also not much different from the electric field around a charge and a dipole/multipole.

[sd79812]

Halbach array. is that any good for understanding why opposite spin electrons, that the magnetic fields actually can cancel in macroscopic reality?