Loving someone without loving God is not really love.   That is just a glorified form of self-love with a lot of mutually acceptable emotions and medium of exchange, kinda' like 2 people holding a mirror to each other so they can admire their own images.

God said that the greatest commandment is to love God, with all your heart and all your mind and all your soul because only the love of God can expand the boundaries of your natural self-love so you can love your neighbor as yourself.  

Needless to say, to love God means to follow and obey the few spiritual truths he revealed to us in order to save our souls because he knows that we can never figure out those things on our own.