After separation, it is not uncommon for one parent to become highly conflictual, creating disputes that appear unnecessary or disproportionate. This behaviour can be emotionally exhausting for everyone involved, particularly when the conflict seems to arise “out of nothing”, never appears to improve, and the familiar reassurance that “she will calm down eventually” simply never materialises.
Rather than viewing this behaviour purely as hostility, bad intent, or dismissing it with modern pop-culture labels such as “the narcissist”, it can be more constructively understood through the lenses of attachment theory and cognitive behavioural therapy (CBT). These approaches help explain why conflict may emerge and persist even when separation was mutually agreed or initiated by the person now displaying high-conflict behaviour.
Separation is not simply the end of a relationship. Two people who once shared the deepest connection possible—creating a child together—do not become “two ships sailing their independent ways”, meeting only briefly to exchange cargo on handover days. It is naïve, and often emotionally dangerous, to expect that such a bond can be undone simply because the shared home or marriage certificate no longer exists.
Separation is also an attachment rupture. Attachment bonds operate largely at an emotional and subconscious level. A person may consciously believe they have no interest in their ex or “their business”, yet those around them often observe a high level of anxiety related to the ex-partner’s life after separation. Even when adults make a rational decision to separate, their attachment systems do not switch off automatically.
For individuals with an anxious attachment style, separation can activate intense feelings of insecurity—often beginning with a loss of identity, followed closely by fear of emotional abandonment and a sense of emotional unsafety. These reactions can occur regardless of who initiated the separation.
It is important to highlight that many of these individuals genuinely enjoy the physical distance from their ex-partner, while being unable to relinquish the need for emotional connection with the person they once shared everything with. Crucially, they are often unaware of this contradiction themselves. To protect their self-worth, they need to believe, “I don’t need the other parent, I’ve moved on, I’m better off”, while simultaneously labelling the other parent a “deadbeat father” or “unfit mother” when that parent is not instantly available.
Anxiously attached individuals often rely heavily on close relationships to regulate their emotions and sense of self. When the relationship ends, the loss can feel overwhelming. The attachment system, designed to preserve connection, becomes highly activated. In this state, the individual may seek ways to restore closeness or relevance to the other parent, even if rekindling the romantic relationship is the very last thing they want.
One key feature of anxious attachment is the tendency to equate emotional intensity with connection. From this perspective, conflict becomes a substitute for closeness. Calm distance, pre-agreed contact, scheduled communication, or strictly practical exchanges may feel like rejection or emotional erasure. In contrast, ongoing disputes over trivial matters, emotional exchanges, prolonged arguments, and even full-blown fights provide reassurance that the other parent is still engaged and responsive. Conflict, therefore, serves as a form of connection rather than simply an expression of anger.
This helps explain why high-conflict behaviour can appear even when the individual was the one who wanted or initiated the separation. Wanting to leave a relationship does not necessarily mean wanting to lose emotional significance in the other person’s life. An anxiously attached parent may struggle to tolerate the emotional distance that follows separation, particularly when the other parent sets boundaries or limits communication to practical matters. The resulting sense of loss and disconnection can lead to protest behaviours such as escalating minor issues, repeatedly raising concerns, or initiating arguments to force engagement.
From a CBT perspective, this behaviour is supported by unhelpful thinking patterns and deeply held beliefs. Common underlying beliefs may include: “If I am not involved, I will be forgotten”, “Silence means rejection”, or “I only matter if I am the one who sets the rules.” These beliefs give rise to automatic thoughts such as “I am being pushed out”, “I am abandoned”, or “They don’t care about me anymore.” These thoughts trigger strong emotional reactions, including anxiety, jealousy, and anger.
Behaviourally, conflict can temporarily reduce these uncomfortable emotions. When an argument provokes a response—when even an unreasonable accusation leads to justification or explanation—the anxious parent feels seen and acknowledged, even if the interaction is entirely negative. This short-term relief reinforces the behaviour, teaching the brain that conflict is an effective way to maintain contact and draw the other parent into prolonged handovers to “set the record straight”. Over time, this leads to more frequent and more intense disputes, often over increasingly minor or symbolic issues.
The situation often escalates further when one parent enters a new relationship. A new partner may be experienced as a significant attachment threat, symbolising replacement, loss of status, and confirmation that the separation is permanent. For the anxiously attached parent, this intensifies fears of being forgotten or excluded from the other parent’s emotional world. Increased conflict at this stage may serve to keep them psychologically present, ensuring they remain a topic of attention and conversation. Even negative attention can feel preferable to feeling absent or irrelevant.
Identity also plays a significant role. For some parents—particularly those who relied heavily on the relationship for emotional stability—separation can result in a profound loss of role and self-definition. Without strong alternative sources of self-worth or effective emotional regulation skills, conflict can provide a sense of purpose, power, or control. Anger may function as a protective emotion, shielding the individual from confronting grief, fear, or emptiness.
It is also important to recognise that many people who display these behaviours lack the skills needed to regulate emotions independently. They may struggle with distress tolerance, emotional awareness, or self-soothing. Conflict becomes the only strategy they know for managing overwhelming feelings. This does not mean the behaviour is intentional or malicious; rather, it is a learned and reinforced coping response.
Understanding these dynamics does not mean excusing harmful behaviour—or justifying it in any way.
Seven years later, I still feel deep bitterness towards my in-laws, who told me that, as a stepmother, it was my duty to accept my partner’s co-parent’s aggressive behaviour towards both of us. They insisted my partner should not set boundaries or consequences in response to her verbal attacks and outrageous accusations. Instead of offering moral support or encouraging stability through therapy and reassurance—which my partner had provided consistently since day one—they justified her high-conflict behaviour and placed me in a constant defensive position.
As a result, there were two women feeling threatened and insecure: the child’s mother, fearing her significance would be taken away by my presence, and me, the new partner, realising that people who were meant to be my family believed abuse towards me was acceptable. With that single message, my sense of safety dissolved.
However, viewing her behaviour through attachment theory and CBT has allowed me to interpret it more constructively. Instead of seeing the conflict as “the bitter ex who hates me”, I can understand that I am not the focus. The conflict exists because of her attachment style—because of how her nervous system responds to change. It is not about me. It is almost never about the specific new partner. No matter how often you are told that you are the problem, or that everything would be better if your partner had chosen someone else, that is rarely true. The response would be the same for anyone who entered the situation without becoming a permanent third member of the relationship.
And this is the key point: never-ending high-conflict behaviour can be understood as a maladaptive attempt to remain emotionally connected and significant during a period of profound change. If a new partner is genuinely comfortable involving the ex as a third emotional presence—something akin to a “sister-wives” or “brother-husbands” dynamic—then conflict may indeed be reduced.
But this understanding must never be used to claim that “good co-parenting” requires everyone to stay emotionally intertwined for the children’s sake. I did not say that, and I never will.
