You ask a question with many, many answers. C.S. Lewis wrote a book called The Four Loves (O’Neill Library BV4639 .L45 1988), drawing on the Greek notions of love in the Bible: Storge (empathy) Philia (friend) Eros (erotic) and Agape (unconditional “God” love). Here’s Shakespeare’s take on it in sonnet 116: bit.ly/shake-love. (Maybe that’s Eros.) One might also note familial love, unrequited love, the love of knowledge (philosophy)… it’s a long list. Which is “real”? I think all of them are. What do they share? The object of love is the focus of total trust & devotion.