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How long does passion last? Science says...

The intense romance you feel at the beginning of a relationship has an expiration date for everyone.
Ryan Gosling Rachel McAdams in "The Notebook"
Ryan Gosling Rachel McAdams in "The Notebook"Everett Collection
/ Source: TODAY

Falling in love is perhaps nature’s greatest high. Just seeing your beloved can make your heart race, your legs weak and your face flushed. Touch him, and well…

Movies try to convince us we’ll feel this way forever, but the intense romance has an expiration date for everyone. Expect the passion to last two to three years at most, says Dr. Fred Nour, a neurologist in Mission Viejo, California, and author of the book “True Love: How to Use Science to Understand Love.”

It’s all about the chemicals in your brain — a potent mix set up by nature to get you to procreate, give birth to a healthy child and take care of him until he’s mature. Despite greeting cards and Valentines, your heart has nothing to do with love. Everything related to love happens in the brain, Nour said. That includes romance — programmed to be fairly short-lived for all of us.

“Romance will never last for a lifetime,” Nour told TODAY. “You have to accept falling in love is just a phase that’s going to go away... If you accept that, you'll have fewer divorces and more happy people.”

Here are the four phases of love:

1. Mate selection

That’s when you’re choosing the person you want to be with. Much of it is unconscious, with instinct guiding you through the process, Nour said. See that one person you’re drawn to in a room full of people? On a basic biological level, you’re attracted to him because your body senses your genes mixed with his genes would produce very healthy children.

2. Romance and falling in love

“This is the phase that everybody talks about, all the movies, all the romance novels, because it’s fun, exciting and thrilling,” Nour said. “In this phase, we don’t see reality — love is blind. We see people as we want them to be, not as they are.”

Brain chemicals called monoamines create that familiar heady rush when you’re with your loved one, or just think of him. Enjoy it because these intense feelings will go away in a few short years, Nour said.

This phase has an important purpose: It prepares you for true love down the road. If you don’t truly fall in love with your partner, you won’t be primed for that last phase, Nour said.

3. Falling out of romantic love

Everyone goes through this stage, even the most adoring, passionate couples you know. In a culture that focuses almost solely on romantic love, it can be very alarming when you realize the rush is gone, the passion has vanished, and your spouse no longer makes your pulse race.

Think of this time as a chance to see your partner for what he really is and decide if you made the right choice.

“Nature made (this phase) for a reason: when you lose the chemicals that give you the euphoria, you start to see reality,” Nour said. “This is a re-evaluation phase. If you feel that, overall, you made a pretty good choice… hang in there.”

People who chase romance and divorce the moment they fall out of love will never experience true love, he said. But if you truly realize you made a mistake, this may be the time to break up and start all over with a new partner. If you don’t fall out of love, you can’t fall in love with somebody else because the human brain is programmed to love one person at a time.

4. True love

If you decide your partner is still the right person for you after the passion ends, you’re on your way to finding true love. It happens gradually and slowly: You'll usually start to feel it one or two years after the previous phase. Your feelings will just continue to grow deeper over the years.

Driven by chemicals called nonapeptides, this stage ensures a deep bond between you and your partner — nature’s way of keeping you together to take care of your kids until they’re grown up, Nour said.

The result is a happier, stronger and longer lasting relationship. This is the ultimate love.

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