Love has not replaced the law. Paul says that the consequences of fulfilling the law and living in love are the same. This is an amazing statement. The law is not the opposite of love, but is consistent with it.
Love does no harm to its neighbor. Therefore love is the fulfillment of thelaw (Rom 13:10).
Love does no harm to another person, so good law cannot allow harm to anyone. A system of government that forces people to do things against their will would be inconsistent with love.
God’s law is the only law that can be fulfilled by love. Good law must be capable of being fulfilled by love. Love could never fulfil a modern system of law, because it would be far to complicated. That suggests there is something wrong with modern systems of law. They cannot be fulfilled by love.