Interpersonal relationships are significantly impacted in individuals with BPD, characterized by a heightened sensitivity to the behavior and actions of others. Individuals with BPD can be very conscious of and susceptible to their perceived or real treatment by others. Individuals may experience profound happiness and gratitude for perceived kindness, yet feel intense sadness or anger[44] towards perceived criticism or harm.[45] A notable feature of BPD is the tendency to engage in idealization and devaluation of others—that is to idealize and subsequently devalue others—oscillating between extreme admiration and profound mistrust or dislike.[46] This pattern, referred to as "splitting", can significantly influence the dynamics of interpersonal relationships.[47][48] In addition to this external "splitting", patients with BPD typically have internal splitting, i.e. vacillation between considering oneself a good person who has been mistreated (in which case anger predominates) and a bad person whose life has no value (in which case self-destructive or even suicidal behavior may occur). This splitting is also evident in black-and-white or all-or-nothing dichotomous thinking.[49]

Despite a strong desire for intimacy, individuals with BPD may exhibit insecure, avoidant, ambivalent, or fearfully preoccupied attachment styles in relationships, complicating their interactions and connections with others.[50] Family members, including parents of adults with BPD, may find themselves in a cycle of being overly involved in the individual's life at times and, at other times, significantly detached,[51] contributing to a sense of alienation within the family unit.[49] Anthropologist Rebecca Lester argues that BPD is a disorder of relationships and communication, namely that a person with BPD lacks the communication skills and knowledge to interact effectively with others within their society and culture given their life experience.[52]

Personality disorders, including BPD, are associated with an increased incidence of chronic stress and conflict, reduced satisfaction in romantic partnerships, domestic abuse, and unintended pregnancies.[53] Research indicates variability in relationship patterns among individuals with BPD. A portion of these individuals may transition rapidly between relationships, a pattern metaphorically described as "butterfly-like", characterized by fleeting and transient interactions and "fluttering" in and out of relationships.[54] Conversely, a subgroup, referred to as "attached", tends to establish fewer but more intense and dependent relationships. These connections often form rapidly, evolving into deeply intertwined and tumultuous bonds.[54] In certain cases, BPD may be recognized as a disability within the workplace, particularly if the condition's severity results in behaviors that undermine relationships, involve engagement in risky activities, or manifest as intense anger, thereby inhibiting the individual's ability to perform their job role effectively.[55] Individuals with BPD express higher levels of jealousy towards their partners in romantic relations.[56][57]

Manipulative behavior to obtain nurturance is considered by the DSM-IV-TR[58] and many mental health professionals[59][60] to be a characteristic of borderline personality disorder.[58] In one research study, 88% of therapists reported that they have experienced manipulation attempts from patient(s).[61] Marsha Linehan has argued that doing so relies upon the assumption that people with BPD who communicate intense pain, or who engage in self-harm and suicidal behavior, do so to influence the behavior of others.[62] The impact of such behavior on others—often an intense emotional reaction in concerned friends, family members, and therapists—is thus assumed to have been the person's intention.[62] According to Linehan, their frequent expressions of intense pain, self-harming, or suicidal behavior may instead represent a method of mood regulation or an escape mechanism from situations that feel unbearable, however, making their assumed manipulative behavior an involuntary and unintentional response.[63]