A few weekends ago, I was enjoying a pretty typical Saturday evening with my fiancé, J. We were cuddled on the couch, watching Netflix in our pajamas. I had one of those crazy sheet masks on my face (super attractive, I know). We didn’t talk much (except to comment on the terrible movie we were watching). From the outside looking in, it might have looked kind of boring. But I felt totally, blissfully comfortable.

J and I have been together for almost four years, and our typical Saturday evening has changed quite a bit over the course of our relationship. In the early days, I would spend pretty much the entire day in anticipation of a Saturday night date; I’d agonize over what to wear and spend hours getting my hair and makeup just right. On the date, we’d talk for hours about anything and everything: our dreams, our fears, our favorite Ninja Turtle (one thing that hasn’t changed over the course of our relationship is the fact that we’re both total nerds). My heart would be racing, my brain going a mile-a-minute wondering if he was going to kiss me.

I loved J at the beginning of our relationship, and I love J now. But the way I experience that love is completely, profoundly different.

So how, exactly, does the way we experience love—physically, mentally, and emotionally—change over the course of a relationship? What causes the shift from spending hours in front of the mirror to make sure you look perfect to “I’m totally cool with you seeing me in my most unflattering sleepwear?” Of course, sometimes we’re still filled with that I-wanna-rip-your-clothes-off spirit. But how do we cultivate that feeling even more when we throw marriage, finances, and all that fun, domestic stuff (“You’re loading the dishwasher the wrong way!”) into the mix?

The Perfect Beginning (a.k.a. the Honeymoon Phase)

When J and I first started dating, it was like a falling-in-love montage in the most clichéd romantic comedy. We would sit across the table, staring googly-eyed at each other for hours. Everything J said was hilarious, insightful, or brilliant (usually all three). When we weren’t together, I thought about the next time I would see him the way a drug addict thinks about their next fix (and as a recovering addict, I know what I’m talking about).

This early can’t-get-enough-of-you phase of a relationship is what’s known as the honeymoon stage, and it can be pretty all-consuming. “In the beginning of relationships, it’s natural that we feel a strong physical attraction and romantic passion,” says Suzie Pileggi Pawelski, MAPP, author of Happy Together: Using the Science of Positive Psychology to Build Love that Lasts.

“You may feel wildly attracted to your partner and can’t keep your hands off one another. You may think about your partner almost to the exclusion of everything else. You may daydream at your desk rather than drafting that important memo… and feel butterflies in your stomach when thinking about them.”

But why, exactly, does the beginning of a relationship feel so consuming? Turns out, my description of feeling like a drug addict in desperate need of a fix is pretty spot-on. “When we first meet someone and feel an attraction to them, a series of chemical reactions are ignited,” says Lyn Rowbotham, Ph.D., a life and relationship coach in Malibu, CA. “We can feel ‘a high’ by the surge of adrenaline, dopamine, and serotonin that our brain releases.”

All of those hormones and neurotransmitters are the perfect cocktail for attraction. Adrenaline enhances our arousal responses, while dopamine increases the brain’s ability to feel pleasure and reward, and serotonin sends a signal through our nerves to boost our mood and sexual desire. And on top of all those feel-good chemicals surging through our bodies, a recent study revealed that people in the honeymoon phase of a relationship had higher levels of nerve growth factor than people who were single or in long-term relationships, which researchers believe can actually increase feelings of euphoria.

(Needless to say, sex in the honeymoon phase is pretty fan-freakin-tastic.)

But as amazing as it is, the honeymoon can’t last forever. Most couples stay in the honeymoon phase anywhere from six months to two years—and experts say that’s a good thing. Because if we want love that’s going to last, it needs to go beyond the honeymoon.

“While feeling completely wrapped up in another person at the beginning of a relationship may be exciting and feel wonderful, it is the relationships that rely solely on passionate love that are doomed to fail,” says Marisa T. Cohen, Ph.D., associate professor of psychology at St. Francis College in New York City and co-founder of the Self-Awareness and Bonding Lab, a research lab that focuses on relationships and social psychology.

“While the couple is experiencing passionate love, it is important to get to know one another on a deeper level, thereby building intimacy-filled companionate love. Being intensely drawn to a person can take you only so far if you don’t build a strong foundation for a long-term loving relationship.”

Reality Sets In

“In the beginning of a relationship, when you are totally absorbed in your partner, you view the world through rose-colored glasses,” Cohen says. And once those rose-colored glasses come off, it can be a pretty jarring experience.

J and I were lucky enough to have a pretty long honeymoon stage, but I remember vividly when it ended—and it was really challenging. Suddenly, we weren’t seeing each other as these perfect creatures incapable of doing anything wrong or stupid or annoying.

We were seeing each other as, you know… actual people. It bugged me that J wanted to be alone when he was upset instead of talking things out. It bugged him that I could be stubborn and unwilling to admit when I was wrong (guilty as charged). Sometimes he would leave dishes in the sink or I would forget to take out the trash, and we would snap at each other.

In other words, the honeymoon was over—and reality had set in.

There was no doubt in my mind that I still loved J; it was just that now that we needed to figure out if our love was sustainable in the long term and if we had the chops to move past passionate love into something more deep and meaningful—what experts call companionate love.

Passionate love is intense, and when reciprocated, is an exciting and wonderful experience,” Cohen says. “Companionate love, on the other hand, is not as intense, but involves a sense of commitment and intimacy—think total self-disclosure, not necessarily sex. Having both present makes for a successful partnership.”

As we navigate through the growing pains of the post-honeymoon phase of a relationship and start to see the person for who they actually are—rather than the fantasy we believed them to be—there’s going to be times we feel more “I-want-to-rip-off-their-head” than “I-want-to-rip-off-their-clothes.” But that’s OK: The important thing to remember during this stage is that even though our feelings might be changing, it’s totally normal.

“Love evolves, of course, from the early-honeymoon passionate stage to the more mature, companionate love,” Pileggi Pawelski says. “We can’t expect the same heightened feelings of positive emotions to exist at the intense levels as it did in the early phases of a relationship.”

In other words, we can’t float on the honeymoon cloud forever. So when the honeymoon inevitably ends and reality sets in, it doesn’t mean there’s anything wrong with our relationship—it just means we have to work to take things to that next level.

Settling Into the Relationship

The honeymoon is great. But what comes after the honeymoon (and after that awkward phase directly following the honeymoon) is arguably even better—the stage when we get comfortable in our relationship.

This is the stage J and I are in now. We’ve been through a lot of life together—we’ve traveled, we’ve dealt with tragedy, we’ve changed jobs and apartments and cities. And the more life we’ve experienced together, the deeper our bond has grown. And with that deeper bond has come a whole new level of comfort and security (which is why I can walk around our house in a sheet mask and frumpy sweatpants with zero hesitation).

We’ve officially reached the companionate stage of love, and like I said—it feels very different from those early I-love-you-so-much-I-feel-high days. But that’s not necessarily a bad thing; while I might not get sweaty palms every time J walks in the room, I do feel a deep sense of gratitude, love, and admiration when he brings home flowers for no reason, when I see him playing with our dog, or when I think about starting a family.

“With familiarity, we get more comfortable with our partner and don’t feel that heightened sense of positive emotions and arousal,” Pileggi Pawelski says. “Our love moves from the higher arousal emotions of interest, amusement, and joy into the calmer positive emotions of serenity, gratitude, inspiration, and awe.”

From a physiological standpoint, the deeper feelings of connection we experience when we’re more settled in our relationship are thanks to changing hormones and neurotransmitters.

As we move from passionate to companionate love, “our levels of adrenaline, dopamine, and serotonin get back to their normal state,” Rowbotham says. They’re replaced by oxytocin, a hormone that’s released as a result of the physical closeness we experience with our partners (think hugging, cuddling, and sex). “Oxytocin can give us a feeling of increased calm and deeper emotional connection to each other.”

Making Relationships Work for the Long Haul

Now that J and I are getting married, I’ve been really curious about how to make the relationship work in the long term. Being happily in love for four years is one thing—but how do we stay just as happily in love 40 years from now?

According to the experts, the key is to keep the spark alive as we continue to deepen our bond—and that means continuing to invest in and work on our relationship.

“We can’t expect for ‘happily ever after’ to just happen or to automatically experience the same burning desire we may have felt at the beginning of the relationship,” Pileggi Pawelski says. “Research shows it’s healthy habits that lead to long-term love.”

So what are some of those habits that can keep us connected, in love, and—yes—wanting to rip off our partner’s clothes for years to come? “Spend time together doing things you both enjoy, together and individually; forgive each other by talking it out; and appreciate each other and let them know it,” Rowbotham says.

“Try your best to be curious about your partner, asking questions, actively listening, and savoring your partner and the small moments,” Pileggi Pawelski says. “Research shows that partners who feel deeply cared for and respected—what they refer to as ‘effectively affirmed’—reported more enjoyment in their sexual relationship.”

According to Cohen, one of the keys to a happy and successful partnership is perceiving your partnership as happy and successful. “Research has shown that couples in stable relationships tend to perceive that their love is growing over time,” Cohen says. “People who experience problems, break up, or are heading toward breaking up perceive their love as declining over time.”

The way we experience love changes over time—and the way I experience my love for J today is totally different than I did at the beginning… and is also completely different from the way I’ll experience it 10, 20, and 40 years from now. Making a relationship work in the long term takes a lot of work, dedication, and commitment to the other person. But what we stand to get out of marriage? Totally worth it.

“A long-term, healthy marriage can offer a deeper sense of security together, a deeper love and understanding of each other, less anxiety about the relationship overall, and a certain level of protectiveness toward each other,” Rowbotham says.

I’ll take that over the honeymoon stage any day.

Deanna deBara is a freelance writer and accidental marathon runner living in Portland, OR. Keep up with her running adventures on Instagram @deannadebara.