When that intoxicating desire is overflowing in the early days of a relationship, all is right in the world. (Comstock)

Oh, sweet, delicious, irresistible lust. Just the word on its own is insatiably sexy.

Go ahead, let it slither off your tongue. Sounds nice, doesn't it?

When that intoxicating desire is overflowing in the early days of a relationship, all is right in the world.

He's perfect. His laugh is infectious, the sex amazing and everything he says is magical.

Even his obsessive love of sports and the way he leaves his socks scattered about his house is adorable.

It's all so good and there isn't a wrinkle, obstacle or single wart in sight ... yet.

WELCOME TO LUST

This chemistry-laden passion also happens to be this scribe's favourite part of all.

Unfortunately, for the lust-addicted, it's also fleeting.

So temporary and delicate, these sensational libido-crazed days will inevitably slip through your fingers.

Then, quite suddenly, you're noticing that his dirty sock trail is actually kind of stinky, that your sex life has taken a dip in favour of the football game, and you've become comfortable enough for the occasional snippy exchange over breakfast bagels.

What's happening here?

Well, it seems Cupid's potent chemicals are wearing off.

Now, don't go pounding the panic button just yet.

According to Helen Fisher, author of Why We Love (Henry Holt and Company), you may actually be falling madly in love.

Fisher says romantic relationships experience three stages, with each one offering up its own special cocktail of chemicals.

Not surprising then that the sex-around-the-clock Lust stage is overrun with testosterone and estrogen, a thrilling concoction that keeps you and your flame stuck together like glue.

SPOT THE DIFFERENCE

Dr. Guy Grenier, author of The 10 Conversations You Must Have Before You Get Married (Key Porter Books), says it's crucial to understand the difference between the glossy fantasy and creating lasting relationship.

"At the beginning, it's hot and obsessive," he says.

"You're Mr. Perfect or Miss Perfect with no warts. A large part of that comes from novelty, but someone can only be novel for six to 30 months -- that's it."

Regardless, I fell in love with lust the very moment I experienced its delectable intensity when, at a New Year's Eve house party, I locked eyes with an Ethan Hawke lookalike (circa Reality Bites).

A tad tipsy, we chatted excitedly late into the night over a shared love of Basquiat, Sonic Youth and New York.

He played drums, I the guitar, and when the clock struck midnight, we shared long exhilarating kisses.

Then, we sobered up.

A few months in, I noticed his banter actually agitated me and that, despite our similar musical tastes, little existed beyond the lust factor.

We didn't even hit round two, known as the Romantic Love or Attraction phase.

Here, the chemicals dopamine (also triggered by cocaine to give you an idea of the high you're on); norepinephrine, also known as adrenaline, and serotonin come rushing in.

It's a time easily identifiable by the fact you're feeling doped up.

In fact, its obsessive power can cause you to forget about everything else because, let's face it, who cares about your to-do list when you could be snuggled up together?

But, all good things must come to an end.

For long-lasting coupledom to occur, the Attachment period must take place.

Here, the powerful bonding chemicals oxytocin and vasopressin get released. Personally, I always grieve the passing of the first couple of stages.

It means more practical sentences, such as, "What do you want for dinner?" start replacing the more impractical approach of wolfing down just enough grub to energize you for another round in the sack.

Why can't we just float around in Cupid's sparkly love dust forever?

Well, you can't, Grenier insists.

CHANGE OR DIE

"Your relationship is always a work in progress," he says.

"It's very Darwinian, but relationships that don't change as a function of their environment go extinct."

Grenier suggests couples do regular maintenance by sitting down and discussing everything from work, family to their relationship five times a week.

I tell him this sounds painfully boring.

"We've got a 40% divorce rate," he reminds me.

Oh, yeah. That.

Still, he insists it's worth the effort.

"There is a great comfort in knowing you're not together because 'Oh, I've got a great package' or 'You've got great eyes,'" he says.

"When there are little ups and downs -- and big ups and downs -- we have history, we've got faith, and we have a commitment to each other ... it's rewarding having someone we feel intimately understands us."

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