You simply have chemical reactions, one of which you like to get mystical about and call love. Sentiments are nice as long as they do not cause us to escape reality. But my experience violently contradicts this world view. I have been the recipient of an unconditional love that was not motivated by either a sex drive or a drive to preserve the human species. I have observed people shower compassion and kindness on handicapped people and terminally-ill patients.
Many human beings love others expecting nothing in return except continued racial slurs or slander.
Love which teaches us how to prepare ourselves to face our awn day of death. Jesus revealed that reality is bigger than matter and energy. Reality includes the supernatural God. This God is love. When God created us he put within us the innate ability to love.