The lines of force have an ability to expand sidewise and contract lengthwise.How does this explain the attraction between unlike poles and repulsion between like poles?

When two like poles come near each other, their lines of forces (bring in the same sence of direction, i.e.  either coming out in both cases or coming-in in both cases) do not cross each other and hence it leads to an unstable situation due to which like poles repel. But in case of unlike poles, the magnetic field lines intersect and go into each other and hence it is a much stable situation and they thus attract.