The problem with defining love is in the classifying, qualifying and quantifying it. It's a lot like saying "what is art?", "I dunno, but I know what I like." Bear in mind that anything can become normal, and all the sh!t men say they'll never tolerate from a woman when single are exactly the behaviors they're conditioned to appreciate (and accept) as her endearing little quirks when they become emotionally involved.
My interpretation of love is simple. There are no classifications for the feeling. All this agape, fraternal, erotic, etc. qualifications are simple lame attempts to define behavior. Love has elements of emotivity, behavioral sets and spirituality of course, but all of these are just manifestations of the same motive. There is no agape love, no erotic love, these are just behaviors and expressions of love not sub-types of love. The same love you feel for your mother, father, sister or brother is the same you feel with a GF, a spouse, the HB 8 you're infatuated with, and the hot piece of ass you banged last night - you simply expressed that love in a different way. I love my mother & daughter intensely, but I ƒuck my wife. It's my manifestation of love that's different. I love my best friend Derek, but I don't ƒuck him, I express that love in other ways. It's not a different feeling, it's a different expression.
When people classify and qualify love they do so because it serves their purpose. This may be profit, this may be insecurity, but whatever the reason it narrows the scope of love. I believe that God is love as well, but God and love are far bigger than our capacities for expressing it. When we insist on pigeonholing, categorizing and forcing our abilities to manifest love on people while saying "this is what love ought to be" we insult the universality of love.