There are relationships in which love seems to enter the house with dirty shoes. First a phrase said to keep the other in his place, then a request disguised as need, then that subtle way of transforming desire into pressure, closeness into possession, the couple into a small field of daily control. In common language all this often ends up in a convenient label, a toxic relationship. It sounds immediate, almost televisual. In psychology, however, certain words are dismantled, measured, inserted into questionnaires, correlated with specific behaviors. And that’s where the picture becomes less vague.
A work published on Journal of Sex & Marital Therapy tried to understand how some antagonistic personality traits are linked to aggression, dominance, risky sexual expectations and coercive behaviors in couples. The study, signed by Judith Antonia Iffland, Lara Katharina Albrecht and Urszula Martyniuk, was published in 2025 in volume 51 of the journal, with DOI 10.1080/0092623X.2025.2557475.
The key word is dark triad. Inside there are three distinct traits, related to each other: psychopathy, narcissism and Machiavellianism. Psychopathy, in this context, concerns high impulsivity, low empathy, difficulty building authentic emotional bonds and a greater tendency towards antisocial conduct. Narcissism brings with it grandiosity, hunger for admiration, hostile reactions when rejection comes or a wound to the self-image. Machiavellianism, named after Niccolò Machiavelli, revolves around strategic manipulation: reading others as pawns, calculating, deceiving, using the relationship as a game to be won.
When the couple becomes territory
To understand certain complicated romantic stories, psychology also looks at adult attachment styles. The basic idea is simple, even if it often hurts: in the first years of life we learn a grammar of bonds, a kind of internal map that then accompanies us in adult relationships. Those who have a secure attachment are able to move with a greater balance between intimacy and autonomy. Those with an insecure attachment may anxiously cling to their partner, or keep their distance to avoid vulnerability. In previous research, high scores in the dark triad are often linked to avoidant styles, where distance serves to maintain control and avoid emotional exposure.
Added to this is a lesser-known, yet very useful concept: relational personality. It means that many people show a relatively stable constellation of attitudes and behaviors with their partner that is different from that used with friends, colleagues or acquaintances. In couples, scripts reserved for intimacy may emerge: request for fusion, dominance, coldness, search for confirmation, aggression, jealousy, need to provoke. Often, without great clarity, we look for partners capable of responding to that very script. Thus we fall back into similar scenarios, even after negative experiences that have already been paid dearly for.
The research group at the Medical School Hamburg tried to give empirical shape to this slippery slope. The sample was made up of 624 adults, 481 women and 143 men, with an average age in the second half of their twenties. The people involved filled out an online survey with standardized tools: a scale to measure psychopathy, narcissism and Machiavellianism, an inventory dedicated to relational personality and attachment, then a scale on sexual aggression and victimization. The sample, as specified in the indexed abstract, was from the general population and completed the Short Dark Triad, Relationship and Attachment Personality Inventory and Sexual Aggression & Victimization Scale.
The questions touched on very concrete aspects. Participants had to indicate their level of agreement with sentences associated with manipulative or emotionally cold attitudes. Then more specific couple tendencies were assessed: need for closeness, desire for dominance, aggression, inclination to respond to a provocation even with physical blows, preferences for adventurous, risky or considered deviant sexual experiences. In the last part, the questions entered the field of sexual coercion: use of physical force, verbal pressure or exploitation of the partner’s inability to resist to obtain a sexual act. The same tactics were also investigated in terms of the victimization suffered.
The results indicate a robust link between the dark triad and an aggressive approach to the relationship. People with higher scores on these traits tended to describe a relationship style marked by physical aggression, rudeness, the need to provoke conflict, and dominance. Among the three traits, psychopathy emerged as the strongest predictor of combative and dominant relationship style. It makes sense, the researchers note, because impulsiveness and poor behavioral control are central parts of that profile.
The dark triad was also linked to sexual expectations. Those who obtained higher scores showed a greater preference for passionate, adventurous and sometimes risky activities. Here too, psychopathy had a significant impact. The hypothesis advanced is that emotional detachment can push towards a more superficial, physical sexuality, less oriented towards tenderness and affective reciprocity. A body close by, a bond kept at a distance.
Control crumbs
On the need for emotional dependence, however, the three traits took different paths. Machiavellianism was positively related to an anxious demand for closeness. People with higher scores on this trait reported greater separation distress and a more intense desire to merge with their partner. Put like this, it might seem like hunger for love. In the researchers’ reading, that proximity can also become a surveillance strategy: staying close to control, monitor, reduce uncertainty, keep the other within a more manageable perimeter. Here mistrust weighs more than care.
The most delicate part concerns sexual coercion. Data shows that dark triad traits are associated with a greater likelihood of reporting sexual aggressive behavior toward an intimate partner. Machiavellianism, in particular, was found to be the trait most permanently linked to the implementation of sexual coercion. The strategic component, combined with low empathy, can favor less visible forms of pressure: false promises, sense of guilt, use of a position of power, words constructed to move the other’s boundary. Abuse, within a relationship, often comes dressed as insistence.
The study also found overlap between those who reported using coercive tactics and those who reported experiencing them. Most people who admitted to sexually coercive behavior also said they had been the target of sexual assault by a partner. The researchers propose a cautious interpretation: those with manipulative traits may first perceive certain situations as coercive, or may feel psychologically manipulated when they feel they are losing control. It is a dirty area, where victimization, perception, defense and domination are intertwined without offering a simple explanation.
In the sample, men recorded higher scores on the dark triad scales than women, a finding in line with some of the psychological literature. Men also reported more adventurous sexual desires. Statistical analyses, however, indicate that the underlying link between dark traits and aggressive behavior in relationships appears substantially similar in the two sexes. The dynamics changes face, retains structure.
Caution is needed, a lot of it. The study is transversal, therefore it photographs a precise moment and allows us to talk about associations, without establishing direct causality. In other words: the data links the dark triad, aggressive relational expectations and sexual coercion, but alone avoids the dry formula of “this causes that”. The same authors indicate that further studies could help assess the risk of sexual assault in intimate relationships.
Then there is a possible selection problem. Recruitment used references to toxic relationships, and this may have attracted people with particularly conflicted romantic histories. Among the female participants, the share of reported experiences of sexual victimization was very high, so much so that researchers considered it unrepresentative of the general population. Those who respond to such a questionnaire often already have a story, a wound, a suspicion, or the need to give a name to something.
Self-evaluation also has its stumbles. Admitting socially reprehensible, and in some cases potentially illegal, behavior is difficult. Those with high traits of the dark triad may also have a greater tendency towards deception and strategic management of their image. This means that some manipulative or coercive conduct may have been scaled back. Sincerity, in a study on manipulation, is already a nervous variable.
For the future, the research team suggests studying both members of the couple at the same time. Looking at just one person offers half the mechanism. Observing two partners together would help understand how the dark traits of one interact with the characteristics of the other, influencing stability, conflict, control, breakups and returns. The relationship is a system, even when it works badly. Sometimes very badly.
One concrete thing remains: certain toxic relationships can seem mysterious only as long as they are described as fate, passion, character incompatibility or “I’m just like that”. When they enter the data, they take another form. Domain. Aggression. Handling. Pressure. Fear of distance. Need to win. Less romantic words, much more useful. And often those are enough to remove love from the pedestal and put it back on the table, where the hands of those who are playing can be seen better.
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