A relationship with BPD can be inconsistent, similar to a roller coaster ride, from feelings of love to abandonment. BPD may distort perceptions, causing antagonistic behaviour. The terror of abandonment and feeling unwanted may be unnerving.

For the partner, their circumstances will adapt to the person with BPD, whether they are “pushing” or “pulling” the relationship. Following a passionate and instantaneous beginning, a volatile relationship often emerges including accusations, anger, jealousy, bullying, control, and a potential cycle of break-ups.

For people with BPD, things are black and white. Fluctuating dramatically between idealising and devaluing, they may suddenly and frequently shift throughout the day. 

People with BPD’s intense, fast-moving emotions can be uplifting yet simultaneously dispiriting. If the partner is in a disagreement with them, they may project their emotions onto their partner. This can translate into vindictive behaviours through certain actions like silent treatment or aggressive words.

Their brains often heighten the intensity and negativity of their perceptions and feelings. It can be made worse when they are alone, hence, they are often dependent on others. They may frequently seek advice, sometimes from several people on the same day, asking the same question.

They react to fears of abandonment with clinging behaviours. They intensely prioritise the feeling of being loved and cared for yet are hypervigilant for any real or imagined signs of rejection or abandonment. Trust is always an issue, often leading to distortions of reality and paranoia.

The partner is either seen as “for” or “against” them and must naturally assume their side. They often behave in ways that can constitute emotional manipulation and, even in some cases, abuse. 

In a close relationship, they must balance the fear of being alone or of being too close. To do so, they may exhibit manipulative and controlling behaviours such as commands or indirect manoeuvres, including flattery and flirting, and using anger and rejection to keep them at a “safe” distance. 

People with BPD are normally dependent, seeking a person who can provide stability and to balance their changeable emotions.  People who seem self-sufficient and in control of their feelings provide a “perfect match”. 

The person with BPD may appear to be the more dependent partner, while their partner is the steady one, but in fact, both are often dependent on each other. It can be hard for either of them to leave. They each exercise control in different ways. Their partners are often co-dependent individuals. 

Partners often become emotional caretakers, sometimes to the point of self-sacrifice or enabling. In the process, partners often give over more and more control to BPD. 

Like all personality disorders, BPD exists on a continuum, from mild to severe. It affects women pre-dominantly more than men, with 75% of BPD diagnoses assigned to women. BPD is usually diagnosed in young adulthood when there has been a pattern of impulsivity and instability in relationships, self-image, and emotions. They may use alcohol, food, drugs or other tactics to attempt to self-medicate.

To diagnose BPD, at least five of the following symptoms must be enduring and present in a variety of areas:

1. Frantic efforts to avoid real or imagined abandonment.
2. Unstable and intense personal relationships, marked by alternating idealisation and devaluation.
3. Persistently unstable sense of self.
4. Risky, potentially self-damaging impulsivity in at least two areas (e.g., of drink or drugs, reckless behaviour, sex, spending).
5. Recurrent self-mutilation or suicidal threats or behaviour.
6. Mood swings (e.g. depressed, irritable, or anxious) mood, not lasting more than a few days.
7. Chronic feelings of emptiness.
8. Frequent, intense, inappropriate temper or anger.
9. Stress-related paranoid thoughts or severe dissociative symptoms.

Often there has been neglect, abandonment, or abuse in childhood and possibly genetic factors. Research has shown brain changes in the ability to regulate emotions. People with BPD usually welcome “help” in efforts to manage their BPD.