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5.4 Maintaining Intimacy

There’s a pervasive myth that passion inevitably dies in long-term relationships. The honeymoon ends, the spark fades, and couples settle into comfortable but passionless routines. It’s presented as an unavoidable fact of life.

But neuroscience tells a different story. Brain imaging studies show that 30-40% of people married over 10 years report being “very intensely in love”—and their brain scans prove it.[1]

Intimacy doesn’t automatically fade. It requires intention. Here’s what the research says about couples who maintain it.

The Desire Discrepancy Reality

Let’s start with the uncomfortable truth: almost all long-term couples experience desire discrepancy at some point. One partner wants sex more frequently than the other. This is normal—not a sign that something is wrong.

A systematic review of 64 studies found that desire discrepancy is one of the most common reasons couples seek therapy.[2] It’s ubiquitous because desire naturally fluctuates based on stress, health, life stage, and countless other factors.

The problem isn’t the discrepancy itself. It’s how couples handle it.

What Doesn’t Work

Research on 229 participants identified five main strategies couples use when facing desire discrepancy.[3] Individual strategies—disengagement, handling it alone, or avoiding the issue—were associated with lower relationship and sexual satisfaction.

Having sex anyway when you don’t want to? Also problematic. It breeds resentment and makes sex feel like an obligation.

What Does Work

The same study found that partnered strategies—approaching the discrepancy as a team problem—predicted higher satisfaction for both partners.

This includes:

  • Open communication about needs without blame
  • Creative compromise (different forms of intimacy, scheduling)
  • Addressing underlying issues (stress, health, relationship conflict)
  • Reframing the narrative from “you don’t want me” to “we have different needs right now”

A 2024 qualitative study of diverse couples found similar themes: couples who navigated discrepancy successfully treated it as a normal fluctuation, not a fundamental incompatibility.[4]

Emotional vs. Physical: The Interplay

Here’s something counterintuitive from a study of 335 married couples:

Sexual satisfaction predicts emotional intimacy—but emotional intimacy doesn’t predict sexual satisfaction.[5]

This challenges the common advice to “fix the emotional connection first.” For many couples, physical intimacy actually builds emotional connection, not the other way around.

The researchers suggest that both domains need attention: “Emotional and sexual intimacy should be comprehensively addressed in research and clinical work with couples.”

What this means practically:

  • Don’t assume you need to feel emotionally connected before being physical
  • Physical affection can rebuild emotional bonds during difficult periods
  • Both partners may have different entry points (one needs emotional connection first, the other doesn’t)
  • Neither approach is wrong—they’re different relationship styles

Your Brain on Long-Term Love

The most encouraging research comes from neuroscience.

A 2012 fMRI study scanned the brains of 17 people who had been married an average of 21 years and still reported intense love for their partners.[6] When they viewed photos of their spouse, their brains showed activity in the same reward regions—the ventral tegmental area, dorsal striatum—that light up in people newly in love.

The brain can sustain romantic passion for decades. It’s not common, but it’s possible.

What distinguished these couples? A related population study found key correlates of sustained passion:[1]

  • Thinking positively about partner when apart
  • Frequent affectionate behaviors (not just sex)
  • Regular sexual activity
  • Shared novel and challenging activities
  • General life happiness

Notice that these are behaviors, not fixed traits. They’re things couples do, not things couples are.

The Self-Expansion Secret

One of the most robust findings in relationship science is self-expansion theory, developed by Arthur Aron and colleagues.[7]

The theory: We’re motivated to expand our sense of self—our knowledge, perspectives, and capabilities. Romantic relationships are a primary avenue for self-expansion. In early relationships, we’re rapidly absorbing our partner’s world, which feels exciting.

Once we’ve absorbed most of what our partner offers, expansion slows. The relationship feels less novel. Passion decreases.

The solution? Keep expanding together.

A 2019 study across three research designs found that couples who engaged in self-expanding activities together reported higher sexual desire than those who didn’t.[8] The key insight: the activities don’t have to be extreme.

Walking in a new neighborhood. Trying a recipe neither has made before. Taking a class together. Learning something from each other.

Couples assigned to do novel activities over a weekend showed greater sexual desire for their partner compared to control groups—even when the activities weren’t physically arousing.

Another study found the mechanism: novel activities work because they promote both closeness and novelty simultaneously—the two ingredients passion requires.[9]

Boredom Is the Real Enemy

In one experiment, the statistical relationship between exciting shared activities and relationship quality dropped significantly when researchers controlled for boredom. Boredom correlated -.58 with relationship quality.[10]

It’s not that passion dies. It’s that routine kills it.

The couples who maintain intimacy are the ones who keep introducing novelty—not through grand gestures, but through consistent small variations in their shared life.

The Power of Non-Sexual Touch

Physical intimacy isn’t just about sex. A cross-cultural study of 7,880 participants from 37 countries found that affectionate touch is the primary way people communicate intimacy, universally.[11]

The physiological benefits are striking:

  • Partners show lower cortisol levels (stress hormone) on days with more physical touch[12]
  • Regular affectionate touch is linked to increased oxytocin and lower blood pressure
  • Increases in physical intimacy lead to decreases in physical symptoms (headaches, muscle tension, insomnia)[12]

The seven types of non-sexual physical affection that predict relationship satisfaction:[13]

  1. Backrubs/massages
  2. Caressing/stroking
  3. Cuddling/holding
  4. Holding hands
  5. Hugging
  6. Kissing on face
  7. Kissing on lips

A study of 1,400 adults found that in long-term relationships, cuddling and caressing contribute more to men’s happiness than women’s—challenging the stereotype that men only want sex.[14]

The implication: non-sexual physical affection may become more important as relationships mature, not less. It maintains the physical bond even when sexual frequency changes.

What This Means for You

If you’re building a new relationship, the research suggests a few principles:

1. Normalize desire fluctuation

Neither partner will always want sex at the same frequency. This isn’t rejection. Approach discrepancies as a shared challenge, not a personal failure.

2. Don’t wait for emotional connection to be physical

For some couples, physical intimacy builds emotional intimacy. If that’s your dynamic, don’t pathologize it.

3. Build novelty into your routine

You don’t need adventure travel. Cook something new. Walk a different route. Learn together. The bar for self-expansion is lower than you think.

4. Maintain non-sexual touch

Hold hands. Hug when you greet each other. Don’t let physical affection become exclusively a precursor to sex.

5. The couples who sustain passion work at it

It’s not that some couples are lucky. The ones who report intense love decades later engage in specific behaviors: thinking positively about their partner, affection, shared activities, sex. These are choices, not circumstances.

Passion doesn’t die from aging. It dies from neglect.

References

  1. O’Leary, K. D., Acevedo, B. P., Aron, A., Huddy, L., & Mashek, D. (2012). Is long-term love more than a rare phenomenon? If so, what are its correlates? Social Psychological and Personality Science, 3, 241-249. doi:10.1177/1948550611417015

  2. Mark, K. P., & Lasslo, J. A. (2018). Maintaining sexual desire in long-term relationships: A systematic review and conceptual model. Journal of Sex Research, 55(4/5), 563-581. doi:10.1080/00224499.2018.1437592

  3. Vowels, L. M., & Mark, K. P. (2020). Strategies for mitigating sexual desire discrepancy in relationships. Archives of Sexual Behavior, 49(3), 1017-1028. doi:10.1007/s10508-020-01640-y

  4. Arenella, M., et al. (2024). Desire discrepancy in long-term relationships: A qualitative study with diverse couples. Family Process. doi:10.1111/famp.12972

  5. Yoo, H., Bartle-Haring, S., Day, R. D., & Gangamma, R. (2014). Couple communication, emotional and sexual intimacy, and relationship satisfaction. Journal of Sex & Marital Therapy, 40(4), 275-293. doi:10.1080/0092623X.2012.751072

  6. Acevedo, B. P., Aron, A., Fisher, H. E., & Brown, L. L. (2012). Neural correlates of long-term intense romantic love. Social Cognitive and Affective Neuroscience, 7(2), 145-159. doi:10.1093/scan/nsq092

  7. Aron, A., & Aron, E. N. (1996). Love and expansion of the self: The state of the model. Personal Relationships, 3, 45-58. doi:10.1111/j.1475-6811.1996.tb00103.x

  8. Muise, A., Harasymchuk, C., Day, L. C., et al. (2019). Broadening your horizons: Self-expanding activities promote desire and satisfaction in established romantic relationships. Journal of Personality and Social Psychology, 116(2), 237-258. doi:10.1037/pspi0000148

  9. Goss, S. C., Raposo, S., Balzarini, R., et al. (2022). Feeling close and seeing a partner in a new light: How self-expansion is associated with sexual desire. Personal Relationships. doi:10.1111/pere.12455

  10. Aron, A., Norman, C. C., Aron, E. N., McKenna, C., & Heyman, R. E. (2000). Couples’ shared participation in novel and arousing activities and experienced relationship quality. Journal of Personality and Social Psychology, 78, 273-284. doi:10.1037/0022-3514.78.2.273

  11. Debrot, A., et al. (2023). Love and affectionate touch toward romantic partners all over the world. Cross-cultural study of 7,880 participants from 37 countries. doi:10.1038/s41598-023-31502-1

  12. Floyd, K. (Multiple studies). Research on affectionate touch, cortisol levels, and physical symptom reduction in romantic relationships. PubMed

  13. Gulledge, A. K., Gulledge, M. H., & Stahmann, R. F. (2003). Seven types of nonsexual romantic physical affection among Brigham Young University students. Psychological Reports. doi:10.2466/pr0.2003.92.3.691

  14. Heiman, J. R., et al. (2011). Sexual satisfaction and relationship happiness in midlife and older couples in five countries. Archives of Sexual Behavior, 40(4), 741-753. doi:10.1007/s10508-010-9703-3