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Many couples today exist in a state of near-continuous contact—shared calendars, location sharing, constant texting, and overlapping friend groups. In many ways, this closeness is exactly what we want from a committed relationship. Emotional intimacy and responsiveness are genuine predictors of relationship health. Feeling understood and securely connected benefits both mental and physical well-being.
But research is beginning to reveal a more complicated picture, one with direct implications for sexual desire.
The conventional wisdom has long been that more closeness equals better relationships. And for many outcomes, that holds. On days when people feel closer to their partner, they also tend to report a higher level of desire. But closeness alone does not explain why so many couples who describe themselves as deeply connected also report fading sexual interest in each other.
The Problem of Low “Otherness”
Relationship researchers Amy Muise and Sophie Goss (2023) propose that what may be missing is something they call “otherness,” defined as the distinctiveness between partners that allows each person to continue seeing the other in a new light, to acknowledge each partner’s unique contributions, and to experience the mystery that sustains wanting. Their central argument: High closeness may be optimally linked to desire only when paired with a sufficient sense of otherness. When closeness is high, but otherness is low, what tends to follow is relationship satisfaction without sexual desire. Warm, stable, and not particularly erotic.
This reframes the problem. The issue is not that couples become too close. It is that they become too similar, too predictable, too fused.
Psychologists call this differentiation the capacity to maintain a clear sense of self while remaining emotionally intimate with a partner. Muise and Goss (2023) review evidence supporting its importance for desire specifically, including longitudinal work showing that women who were more differentiated reported a higher amount of sexual desire over the course of a year, as did men who perceived greater differentiation between themselves and their partners. When couples were asked directly what helped them maintain desire over time, autonomy consistently emerged as a key theme, described as having personal projects, physical distance at times, or simply the psychological sense of recognizing a partner as a genuinely separate person. What most eroded desire, by contrast, was overfamiliarity: knowing someone so thoroughly that they no longer surprise you.
Partners Need to Witness Each Other’s Growth
Self-expansion theory offers a complementary lens. People are fundamentally motivated to grow their sense of self, and relationships are one of the primary vehicles for that growth (Emery, Hughes, & Muise, 2025). Early in a relationship, a partner is a rich source of self-expansion: new perspectives, new skills, new ways of seeing yourself. Over time, that source becomes finite. When couples stop expanding together, boredom and disengagement tend to follow. Importantly, Emery and colleagues (2025) note that when people chronically self-expand outside the relationship rather than within it, passion tends to decline. The goal is not to have separate growth at the expense of the relationship. It is growth that partners can witness and remain curious about together.
Modern technology can quietly work against this. Couples who remain in near-constant psychological contact through texting and social media have fewer natural opportunities for independent experience, reflection, or development. When every thought and feeling is immediately shared, there are fewer moments of re-encountering a partner as someone who has changed or surprised you.
The Importance of Autonomy
This is not an argument for emotional distance. Attachment research clearly shows that security within a relationship is what enables exploration.
A 2025 daily diary study following two samples of long-term couples over 21 days and again three months later found that people who reported feeling less free to be themselves in daily interactions with their partner reported lower relationship satisfaction at both time points (Genesse et al., 2025). Feeling autonomous in a relationship, meaning acting in accordance with your own values, preferences, and genuine self, was one of the strongest daily predictors of relationship well-being. The research also revealed a partner effect: When one person consistently suppresses their autonomous self, it tends to diminish their partner’s sense of autonomy too (Genesse et al., 2025). Over-merging is contagious.
The healthiest couples in the research literature tend to support each other’s independent friendships, interests, and ambitions. They remain genuinely curious about each other’s inner lives. They continue to change in ways the other person notices. They do not become one. They remain two people who keep becoming, and who find each other interesting because of it.
Intimacy at its best deepens the self. It does not dissolve it.
If desire in your relationship has gone quiet, the question worth asking is not only how connected you are. It is whether there is still enough otherness between you, enough distinctiveness, enough room for each of you to keep growing, for the relationship to remain a place of discovery rather than only of comfort.
