Why north pole of a magnet didn’t like north pole what exactly happening inside the north pole ?

The first thing to keep in our mind is that the magnetic force because of the magnetic field is present around the bar magnet. These field lines are directed from N to S pole direction.

Now refer to the image, Here you can see the magnetic field lines from the N poles of the two magnets are colliding head to head with each other. So these field lines are hitting each other way before the magnets physically touch each other.

Same for the opposite poles, they attract each other before they hit. Hope it helped.