Why Some Couples Feel More Like Roommates Over Time, According to Personality Science

Feeling more like roommates than lovers over time, even after years of being head over heels for each other, is more common than you might think. If you’ve lived it yourself, or heard a friend lament it, you know how dispiriting it can feel. One day, it’s all sparks and butterflies, and a few years later… it’s two people living under the same roof and arguing over whose turn it is to wash the dishes. Maybe the scientists are right and love is just nature’s trick to make us make babies.

And yet, there are couples who’ve been together for decades and are still deeply in love long after biology has done its job. Maybe not in that “can’t-keep-their-hands-off-each-other” frenzy of the early days, but in a calm and steady way that’s just as real. 

Personality science might hold some clues about why some relationships slide into the “roommate” phase while others continue to thrive. Let’s explore this through the lens of the Big Five personality framework. As a reminder, the Big Five is a widely researched personality model that describes human personality across five key dimensions: Openness, Conscientiousness, Extraversion, Agreeableness and Neuroticism. Each person falls somewhere along a spectrum for each trait, meaning we all have our own unique blend. The Big Five framework helps researchers understand the stable patterns in how people think, feel and behave—and it can also shed light on the subtle personality differences that influence how couples connect (or disconnect) over time.

Conscientiousness: When Love Becomes a To-Do List

Research shows that people who score higher on Conscientiousness tend to have more satisfying relationships. The authors of this study say it’s because highly Conscientious people —those who are organized, responsible and disciplined—usually try hard to become better partners and to fix their mistakes when something goes wrong in the relationship. Because they put in this effort and care about doing things right, they are often more motivated to keep their marriage or relationship healthy and strong.

However, high Conscientiousness can sometimes lead to the “roommate effect” down the road. One study found that if someone starts out Conscientious, it doesn't always mean their marriage will keep getting happier over time; sometimes, it might actually predict drops in satisfaction as time goes on. The researchers didn’t spell out exactly why, but it’s easy to see how this might happen. When that hyper-organized, “do the right thing” mindset associated with trait Conscientiousness takes over, the focus can shift from blazing-hot love to chores, finances and schedules. Before long, a relationship can start feeling more like a functional roommateship rather than a romantic union.  

Interestingly, this study found that husbands (but not wives) tend to get more Conscientious in the first few months of marriage, which is also the time when couples start noticing the first dips in romance. Again, the researchers didn’t explain why, but one plausible reason is that husbands often assume the traditional provider role—they take on more of the day-to-day responsibilities of running life together, though of course that doesn’t apply to all couples.

Openness: When Routine Replaces Romance

One thing that defines the beginning of all romantic relationships is newness—new routines, new conversations, new bedtime rhythms, new food, new music, even new ways of seeing ourselves. This flood of novelty activates the brain’s reward system, especially dopamine pathways, which fire up when we experience something new, uncertain or full of potential.

But over time, our brains habituate to the new stimuli, making them feel… well, not so new anymore. The dopamine that once made your partner’s touch feel electric now gives way to a calmer, more familiar glow. ​​The reason some couples navigate this transition smoothly, where their fiery early passion evolves into a steady, lasting intimacy, while others start feeling more like roommates, may come down to the trait of Openness to Experience. 

Research shows that people higher in Openness tend to maintain higher levels of relationship satisfaction over time. This is likely because they naturally seek out new experiences, which helps them make up for the loss of novelty and excitement that inevitably comes with getting used to their romantic partner. In contrast, those low in Openness tend to stick to routines and familiar patterns, which over time can make a relationship feel more predictable and “roommate-y” once the initial novelty wears off.

As couple therapist Esther Perel puts it, "Novelty is a powerful aphrodisiac. In long-term relationships especially, cultivating novelty—whether through stories or experiences—is key for sustaining passion. Maintaining a sense of mystery and surprise helps counteract the routine and repetition that can sometimes lead to a decline in desire over time."

Neuroticism: When Lover Becomes a Roommate You Can’t Stand

While there’s this idea that people tend to mellow out and grow more at peace with themselves over time, studies show that Neuroticism can actually increase with age as the challenges of life pile up around them. Neuroticism describes how often a person feels negative emotions like anxiety, self-doubt or sadness, and how emotionally reactive they are to stress and challenges. As you might expect, higher Neuroticism doesn’t exactly lend itself to a happily-ever-after. 

Research suggests that increases in Neuroticism are associated with declines in marital satisfaction, and the relationship appears to be bidirectional. In other words, as a person becomes more Neurotic—whether because of a stressful life event or just the daily grind—their heightened negative emotions can spill over into the relationship, which in turn may further increase their Neuroticism.

Over time, it’s not hard to imagine how this vicious cycle can turn the person you were once head-over-heels for into someone who feels more like an annoying roommate you’re just trying to avoid.

Agreeableness and Extraversion

Agreeable people usually report higher relationship satisfaction, which is not surprising since Agreeableness measures how kind, cooperative, empathetic and willing to compromise someone is. When it comes to feeling like roommates over time, there doesn’t seem to be any solid evidence that Agreeableness is the culprit. In fact, research shows that Agreeableness may increase slightly as we get older, which might help explain why some long-term couples manage to stay peaceful and cooperative even if the spark isn’t as intense as it once was. In other words, being more Agreeable can make partners feel like “good roommates” in the sense that life together runs smoothly, but that’s not the reason why some couples drift into the roommate phase. 

As for Extraversion, multiple studies show that it’s generally linked to higher relationship satisfaction, possibly because it acts a bit like Openness—Extraverted people will actively seek out shared adventures and exciting social experiences. But when it comes to feeling like roommates over time, it doesn’t seem to play much of a role.

Final Words

At the end of the day, we already know what makes some couples shift from passionate love to feeling like roommates over time, and we don’t necessarily need scientists to tell us. It’s a common saying that “familiarity breeds contempt,” and another that “variety is the spice of life.” Time and routine can slowly suck the spark out of any relationship and, while running a household and pursuing shared goals are important, they can also drain spontaneity and passion.So, it’s reassuring when research backs up what our gut instincts already know. 

This doesn’t mean that all couples are destined for roommate territory. Desire and intimacy can always be rekindled, even as the years pass and routines settle in. All it takes is effort, and you control how much you put in, whatever your personality type.