Then the dark matter pre-existed and the laws and formulas governing gravity and EM were based upon incorrect assumptions, and thus incorrect. It is those laws and formulas that have been applied to a multitude of other observations and interpretation of cause and effect, meaning how things are put together and the processes involved. And to human cosmological beliefs. The modern phyiscs model is covered in so many Band Aids you can't see the object anymore.<quoted text>
The need of dark matter as an explanation was based on observation.
There is indirect observation the dark matter hypothesis is correct. So you have it simply like this, dark matter exists and is the reason gravity is stronger over distance than thought.
The inverse square law is wrong . Or it is something else causing it. It doubtful the inverse square law could be that wrong , or space flights would have detected it. That leaves two things , do you want to try to explain it?
Hint many people have tried to apply various hypothesis using magnetism and em but it doesn't work.