In the course of electrostatics I have come across a basic condition to hold the superposition principle for electric fields, and that is the electric field of one charge should not affect the field of others, that is the first criterion, may be the charges should be placed a minimum distance apart so that one's field can't affect the other field ,and principal of superposition holds perfectly.
Now suppose I have two equal and opposite charges, $+q$ and $-q$, and I place them at distance $d$ from each other. Now, say $d$ is large now so that superposition principle holds, and now I decrease $d$: watching the field vs time, I should see that at first the superposition principle holds, but by the time that $d$ decreases by a significant amount, then it becomes dipole. Now the electric field of a dipole can't be written as sum of two electric fields.
Now my question is how just that happened? All of a sudden the superposition principle does not hold? So what is the deal with the distance between them?
And if the distance should be small for it to be a dipole, then small with respect to what?
If it should be small with respect to field point then what would happen if I place those charges far away from each other but my field point (where I am checking the electric field) is at even further away from them, will then they form dipole?
If the small distance is with respect to something then dipole field is not absolute it is relative! But it makes me crazy and confused. Too much.