From the vantage point of my age love is completely different from how I would have defined it what I was young. And even then, how do you define love? It is even more difficult than defining children's literature: everyone know what it is, but try to define it, and you are lost.
I have been reading some cognitive psychology recently. Human emotions are results of chemical processes in our brain caused by the degree of achievements of our goals through our actions. Happiness is a basic emotion that occurs when our individual goals are successfully achieved. Love is a social emotion based on interaction with other individuals. Love is the desire to have your own goals incorporated with the goals of another person. This sounds very dry, but if you consider what it means, you wish someone else to be happy together with you, on equal conditions. If you don't care about the other person's well-being, it's not love. If your emotion is self-destructive it's not love either. This makes much better sense to me now than it would do when I was young. My love for my partner implies a balance of our well-being, which is extremely difficult to achieve, even after many years of training. My love for my children implies that I wish them well without necessarily sacrificing myself for their sake (of course I would in an extreme situation). Love is hard work rather than a gift from heaven. But I wouldn't have believed this when I was young.