This is because human love, is rooted in the Divine attribute of Chesed (lovingkindness). Since G-d is constantly bestowing His kindness upon creation, feelings of kindness and love, always abound in the world. They can drive man to incredible heights, or to the lowest depths.

If love is properly controlled, it is the most effective tool for the building of humanity and peace. Thus the verse states "The world is built through Chesed".