Why proton doesnt repll each other in nuclous of an atom?

Actually, they do repel each other in the nucleus of the atom because of the electromagnetic force that all protons possess. The thing is that they are being held down and is counter-balanced by another force which is known as the strong nuclear force. The neutrons inside the nucleus of an atom would serve this purpose just like a buffer. If neutrons were absent or isn't enough in numbers, especially to atoms that are larger in size, then it would eventually break.