There's a fine line between intensity and obsession. Now, a lot of people think they want intensity. Think of the scene in You've Got Mail where Tom Hanks is saying "we could go have coffee, or dinner, or a movie ... till death do us part". There's a closeup of his gaze, huge brown eyes, puppy dog face, concentrating the whole of his attention on you. Well, really on Meg Ryan. Well, technically, on a movie camera. But the emotional effect is there (it's called acting). And it's wonderful. You sit there and think how nice that would be, to have someone so totally involved with you.

But real life isn't the movies. Sometimes the time isn't right. "I don't have time for romance right now! I'm busy!" Sometimes the person isn't right -- or just seems that way (the whole point of many films). Or it just isn't what you want.

No, in real life, most of us flee that kind of intensity. The same passion that inspires great art, that fuels the most romantic love affairs, teeters on the brink of obsession. The dark side of desire, the force that motivates an artist to cut off his own ear, the feelings that make an admirer into a stalker.

Most people have felt that sort of intensity. That's what a crush is -- your emotions are so powerful it seems like you can't contain them. Nobody else can possibly understand what you're feeling. And it's true -- if you're not having a crush on someone right now, your memory is but a pale ghost of the real thing. And crushes are fleeting -- literature is full of admonitions that the ephemeral incandescence of a new relationship is destined eventually fade to the glowing embers that sustain lifelong love, or go out completely.

But some of us are different. Some of us can maintain a crush indefinately. But, in a vicious irony, that very thing, the stuff of romance novels, what many people say they crave, drives people away. People who've been shunned while they still have a crush on someone know the special pain of having the most incredible feelings they've ever experienced suddenly turned upside down, to become sharp, wrenching pain. The kind of pain that you can't forget. Everything reminds you of the horrible blow you've suffered, the loss, the loneliness, the total unfairness of it all.

But if you're one of those for whom a crush doesn't fade, you can't escape it if the relationship doesn't survive. And most such relationships don't, because most people, faced with unfading passion, get frightened and run away. Because, from outside, it's hard to tell the difference between a long- term crush and obsession. It's a sad truth, but the pinnacle of romantic love is often mistaken for a dangerous mental instability.