Inertia
In much the same way, the force of inertia is not explained
by Newton’s universal gravitation.
Inertia is the name for the increased effort that is required to move any
object from rest. The dark matter has to get out of the way when a molecular
object is moved. An additional starting force is required because the dark
matter is very lightly bonded together. As the dark matter is effectively
massless, then once the body is in motion, the dark matter continues to move
around it without extra effort. This is one reason to believe that the dark
matter has a structure of its own. The initial movement through that structure
requires an inertial force, as the infinitely small bonds are broken.