The entire bible, God is about love. Love is that thing that keeps everything together. God put the tree in the middle of the garden to give Adam and Eve a choice. If one has no choice in love it would not be love in the first place. That is why God put the tree in the garden of eden to test them and to find out if they really love God. That is what sucks so much about the lust of the flesh, the pride of life and the lust of the eyes. Its not love its lust wherewith most people struggle. Love is everything that is good according to the bible. Without love you can not see God. If a man loves God he loves his neighbor as well. So the reason why God put the tree in the Garden of eden was to test the love Adam and eve had towards Him.