Couple relationships and Borderline Personality Disorder: examining the interpersonal experience of caregiving partners and people diagnosed with BPD

Borderline Personality Disorder (BPD) is a mental condition characterised by emotional lability and turbulent interpersonal connections [1]. People diagnosed with BPD have more relationships characterised by a major change or

termination compared to healthy individuals and those with other mental health conditions [2, 3] and BPD features are associated with received and perpetrated abuse within the couple [4]. For many individuals diagnosed with BPD-more than a third of

whom are in long-term romantic relationships [5]- spouses and romantic partners are the main providers of care [6]. Recent

studies highlighted the reciprocal relationship between the quality of interpersonal relationships and the severity of BPD features

[7]. Further, carers of people with BPD experience a higher carer burden than carers of people affected by other mental illnesses [8, 9] which, in turn, negatively impacts relationship quality and stability. The changing perception of relational dynamics that is typical of the disorder, along with its interdependence with BPD

features and the role of the partner-caregiver, gives rise to a complex interpersonal context that is yet to be investigated

qualitatively. The available interventions for BPD couples are limited and largely informed by theoretical models rather than

grounded on couples' experience [10]. Gaining insight into the experience of both caregiving partners, and people diagnosed

with BPD in a romantic relationship will provide the experiential ground necessary to model relationship-centred interventions

based on the couple's needs, improving clinical outcomes and general wellbeing. Researching this area is particularly relevant

considering that psychotherapy is the first-line treatment for BPD [11] and that this disorder has a prevalence of 1.6% in the general population [11]. The core clinical domains of BPD are a reinforcing and maintaining factor of disordered affect [12]. Specifically,

difficulties regulating emotions, a lack of tolerance, awareness and attentional impulsiveness are central and interrelated features

of the condition and contribute significantly to interpersonal problems [13]. Conversely, stable marital relationships and short-term functioning romantic relationships seem to act as protective factors leading to improved functioning, decreased anger, higher employment rates, and improved sexual functioning [14-16]. Importantly, emerging quantitative research shows the

dynamic and fluctuant nature of the correlation between relationship quality and BPD symptoms over time [7] which is typical of many other features of the disorder including the diagnosis itself [17]. The correlation between BPD features and relationship quality is most important among frequent-interaction partners

(e.g. romantic relationships) [7]. BPD symptoms are associated with dysfunctional interactions within couple relationships leading to lower marital satisfaction, higher attachment insecurity, more demand-withdrawal communication problems, and

higher levels of intimate violence than in non-clinical couples[4]. Interestingly, both partners (not only the one with BPD) adopt similar levels of dysfunctional behaviours contributing equally to negative interactions [18]. In summary, there is not a comprehensive understanding of the intertwined experiences of caregiving partners and

people with BPD cared for by their partners. No research, to date, has captured the fluid and fluctuant nature of these interpersonal experiences that represent a core domain of BPD and, therefore, should inform effective psychological interventions. To

understand this aspect, it is fundamental to research this qualitatively - because interpersonal relationships reflect a key context,

are reciprocal and shift over time. It also requires an idiographic, holistic, and in-depth approach like Interpretative Phenomenological Analysis (IPA) - because it is profoundly personal.