Philosophy of Love

Love is a fundamental aspect of human existence. It is a central principle to every discussion on happiness. The philosophy of love asks about the nature and kinds of love. What is love? Is it an emotion or a choice? If nonegoistic love is possible, then how so? If there different kinds of love, then what are they?  The problem of love is the perennial dilemma centered around egoism and altruism, self-interest and self-denial, self-centeredness and disinterestedness. What is the proper relationship between the love that one bears for oneself and the love that one bears for another human or for God?