Why Sex Gets Harder When Love Gets Safer

Sex is important in a romantic relationship because it is not simply a pleasurable activity that two people happen to do together. In an established sexual relationship, sex sits at the intersection of the brain’s sexual, attachment, reward and caregiving systems. Research on human attachment describes pair-bonding as involving interacting oxytocin and dopamine systems, together with neural networks involved in reward, motivation, emotional salience and social connection.  Sexual intimacy therefore provides a particularly powerful context in which the brain repeatedly associates a particular person with pleasure, safety, reward and closeness. In simple terms, sex is one of the ways the nervous system learns, this is my person.

Sexual intimacy is also a form of co-regulation. Humans regulate distress partly through other humans, and affectionate physical contact can alter both subjective distress and physiological stress responses. Partner touch has been associated with reduced cortisol and cardiovascular arousal, while experimental work has found that holding a partner’s hand can reduce neural responses to threat.  Affective touch engages neurobiological systems involving oxytocin, endogenous opioids, dopamine and autonomic regulation. Sex brings many of these regulatory signals together at once: sustained skin-to-skin contact, warmth, pressure, rhythmic movement, eye contact, kissing, scent, affectionate touch and, often, orgasm followed by prolonged physical closeness. It can therefore function as an unusually concentrated form of interpersonal soothing and nervous-system regulation.This matters because attachment is not maintained solely through cognition. 

Knowing intellectually that your partner loves you is different from repeatedly experiencing them as a source of safety, pleasure, comfort and embodied connection. Romantic touch itself is processed differently according to who is touching us, and research suggests that neurochemical systems involved in bonding can increase the reward value of a partner’s touch. Over thousands of repetitions, touching, kissing, sleeping together and having sex become part of the couple’s implicit attachment language. The relationship is therefore being maintained not only through conversations and shared values, but through repeated bodily experiences of approach, responsiveness, pleasure, safety and return.

Sex also does something psychologically distinctive: it continually differentiates the romantic relationship from friendship, co-parenting, household management and companionship. Couples can love each other profoundly while gradually becoming excellent colleagues in the business of running a life together. Sexual intimacy creates a recurring space in which the partners encounter one another specifically as lovers. It involves attention, vulnerability, responsiveness, desire, play and embodied mutuality. Unsurprisingly, sexual satisfaction and relationship satisfaction are closely intertwined, and longitudinal research has found that sexual satisfaction can predict subsequent relationship satisfaction. 

One of the largest analyses in relationship science, involving 43 longitudinal couples datasets and more than 11,000 couples, identified sexual satisfaction as one of the five most reliable relationship-specific predictors of relationship quality, alongside perceived partner commitment, appreciation, perceived partner satisfaction and conflict*.

For that reason, when sex is medically possible and both people entered the relationship understanding it to be a sexual one, the prolonged disappearance of sex should not automatically be dismissed as superficial, demanding or unimportant. Nobody should have sex they do not want. Equally, a partner is allowed to say that a permanently sexless relationship is not a relationship in which they can remain fulfilled.The useful question, therefore, is, “What has happened to the sexual bond between us, and are we both willing to participate in rebuilding it?” Attachment style, responsive desire, resentment, exhaustion, parenting, stress, medication, hormonal changes, pain, trauma, body-image difficulties and unresolved relationship injuries can all interfere with sexuality. 

Those problems deserve curiosity and treatment rather than accepting reluctance through guilt, duty, or obligation. But treating sexuality as irrelevant misses something fundamental: for many couples, sex is one of the principal mechanisms through which attachment is embodied, partners co-regulate one another, and two people continue to experience themselves not merely as people who love each other, but as lovers.

Keeping a long-term relationship sexually vital requires couples to understand that desire does not necessarily look after itself. Esther Perel describes one of the central paradoxes of long-term love: the qualities that create secure attachment, such as familiarity, predictability, closeness and dependability, are not necessarily the same qualities that generate erotic desire.  Desire also needs imagination, anticipation, novelty and enough separateness to continue experiencing one's partner as another person rather than simply as a familiar part of everyday life. Couples therefore need to protect an erotic space within the relationship, one in which they continue to encounter one another not only as parents, companions and co-managers of a household, but as lovers.

Importantly, sexual vitality starts with the individual, not the couple. One of the most useful questions is not simply “Am I desirable to my partner?” but “Do I feel desirable to myself?” This is less about conventional attractiveness than about embodiment and aliveness. Do I feel connected to my body? Do I move it, inhabit it, dress it and care for it in ways that make me feel alive? Do I have interests, pleasures, friendships and experiences that remind me that I am a whole person outside the demands of work, parenting and domestic life? Eroticism is difficult to access when someone experiences themselves primarily as an exhausted worker, caregiver or household administrator. Sex begins with having access to one's own sensual and erotic self.

Couples also need liminal space, periods in which nothing sexual is required but something sexual could happen. Modern couples are remarkably good at eliminating this space. Every hour becomes allocated to children, work, devices, chores, exercise or rest, and sex is somehow expected to materialise spontaneously in the twelve minutes remaining before somebody falls asleep. Sexuality needs unclaimed time. This does not necessarily mean scheduling sex (unless that turns you both on). It means deliberately creating periods of privacy, proximity and low demand in which partners can talk, lie together, shower together, listen to music, watch the fire, wander into bed or do absolutely nothing. The important thing is that there is somewhere for desire to land if it appears.

It is also enormously useful for couples to understand the difference between affection and flirtation, both in how they offer and receive them. Affection says, “I love you, I want to be close to you.” Flirtation carries an erotic possibility: “I am approaching you as a lover.” Problems arise when couples lose the ability to distinguish between the two. A partner may reach for a cuddle, kiss or affectionate touch with absolutely no sexual agenda, while the other experiences it as the beginning of an initiation and immediately feels pressure to either reciprocate sexually or reject them. 

Over time, the anticipation of “they're hankering for something else” can lead someone to avoid even ordinary affection, while their partner becomes increasingly deprived of both affection and sexual connection. Couples benefit enormously from explicitly understanding how each person gives and receives affection, how each person signals flirtation, and crucially, how they communicate “this is just affection, there is no expectation attached to it.” This allows affectionate touch to become safe again while preserving a separate pathway through which erotic interest can be communicated.

Long-term couples can also encounter what I think of as the erotic vulnerability paradox. If we imagine two lines across the lifespan of a relationship, emotional intimacy may steadily increase while sexual openness, experimentation and erotic risk-taking gradually decline. At first this seems counterintuitive. Surely the person we trust most should also be the person with whom we feel most sexually uninhibited? Yet increased emotional intimacy also means increased emotional stakes. 

Early in a relationship, there may be comparatively little to lose. Years later, this person knows you intimately, matters enormously to you, shares your home, your history and perhaps your children, and, inconveniently, will still be sitting opposite you at breakfast tomorrow morning, possibly thinking about (God forbid) what you disclosed last night. Or not thinking about it at all, which may somehow feel even worse.

The result is that couples can actually become more sexually shy with one another as they become more emotionally intimate. Revealing a fantasy, asking for something unfamiliar, initiating in a new way or exposing a previously private part of one's sexuality now carries the possibility of embarrassment, rejection or shame in front of the person whose opinion matters most. This is not necessarily enmeshment, loss of differentiation or lack of attraction. Sometimes it is almost the opposite: there is more to lose. Maintaining sexual vitality therefore requires couples to recognise this paradox and deliberately create an erotic culture in which vulnerability is handled gently, experimentation is welcomed, awkwardness is survivable, and an unsuccessful sexual bid does not become a referendum on either person's desirability or the relationship itself.

Just as importantly, partners should communicate when they should not be approached sexually. This is an extraordinarily simple way of interrupting the damaging initiation-rejection cycle. If one partner repeatedly initiates at times when the other is predictably unreceptive, one accumulates rejection while the other accumulates pressure. Eventually the higher-desire partner becomes frightened of initiating and the lower-desire partner becomes vigilant about being approached. Neither response is conducive to eroticism. Knowing, for example, “Don't initiate when I've just walked in from work, but Saturday mornings are usually good” replaces mind-reading with useful information and protects both partners from unnecessary experiences of rejection.

Emily Nagoski's work is also useful because couples need to stop assuming that desire must precede sexual engagement. For many people, particularly in established relationships, desire is responsive: erotic interest emerges once the nervous system encounters something worth responding to. Stress, resentment, exhaustion, parenting demands, work pressures, lack of privacy and cognitive load can all operate as powerful sexual brakes. Rather than repeatedly asking “Why don't I feel like sex?”, it can be more productive to ask “What conditions allow my erotic system to come online, and what consistently switches it off?” Couples can then work collaboratively on creating those conditions rather than treating differences in desire as evidence that somebody is defective or no longer in love.

Finally, we need to be able to talk intelligently about sex differences without pretending they do not exist. Men and women overlap enormously and individuals must always be understood as individuals, but population-level research does identify average sex differences across aspects of sexual desire, motivation, arousal and sexual behaviour. Those differences interact with hormones, reproductive biology, learning, culture, attachment, safety, relationship history and social expectations. Ignoring them is no more useful clinically than treating them as rigid rules. The task is to understand what sex actually means to each partner. For one person, sexual contact may be one of the primary ways they experience love, reassurance, acceptance and emotional closeness. For another, emotional connection and feeling understood may be prerequisites for becoming sexually receptive in the first place. Neither sequence is inherently superior. Problems arise when each partner assumes the other's sexual system should operate like their own.

Ultimately, long-term sexual vitality requires couples to protect both attachment and eroticism. They need safety without allowing familiarity to become erotic invisibility, closeness without abandoning individuality, and enough predictability to trust one another while preserving enough uncertainty, play and curiosity for desire to remain possible. The goal is not to reproduce the neurochemical intensity of the first six months. It is to continue creating a relationship in which two people feel sufficiently safe to belong to one another, sufficiently separate to desire one another, and sufficiently brave to keep revealing who they are sexually as both of them change.

*https://www.pnas.org/doi/full/10.1073/pnas.1917036117

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