Question

why dipole field drop off more rapidly with distance 1\r3 then 1\r2

Answer 1

if you see the efield lines.. u can see, that since there is a positive and negative charge,
the field lines keep moving away from each other, much quicker (with distance) compared to normal radial field lines due to just a point charge

see.. m showing field line due to dipole (left side.. field line of +charge i have drawn) and field line due to a monopole, a point positive charge (of same strength) on right side