I don't believe that love has to be defined in a spiritual context. It's an emotion, how do you define anger, happiness, etc? We all have our own definitions.
Love to me is caring about someone or something beyond yourself and your own needs. It's being willing to let someone go and live a different life without you because you both will be better off in the long run. It's discipling a child when you know they are hurting themselves when it would be easier to just let it go. It's telling a friend or family member "No" when you know your help would just keep them on the same self-destructive road.
I also believe you can't have love without hatred. Funny how some of the people we have loved the most become the most hated. A very good friend of mine for most of my life once said "There's a very fine line between love and hate", we don't talk anymore and it's because we let things go too far because we cared about each other too much to tell each other what we felt.