Problems with interpersonal relationships are common to all personality disorders. Experts consider these interpersonal difficulties to be the most significant and defining feature that all personality disorders share.
Quite logically, the three defining features described above (i.e., problems with thinking, emotional regulation, and impulse regulation) cause significant interpersonal difficulties. These problematic thoughts, feelings, and behaviors converge to create a very negative impact on people's ability to fulfill social roles, and their ability to form and maintain healthy and rewarding relationships.
Previously, we suggested two core features of personality disorder, affective (emotional) regulation and impulse regulation, could be understood along a single continuum of regulation. At one pole of this regulation continuum is extreme over-regulation (of emotion and/or impulsivity).At the other pole is extreme under-regulation (of emotion and/or impulsivity). In other words, there is a single dimension of regulation ranging from very high to very low, with personality disorders falling at each end of the continuum, and healthy personalities falling somewhere in the middle of these two extremes.
However, the interpersonal problems associated with personality disorders are a bit different. Instead of a single dimension, some experts believe that two dimensions are necessary to properly describe these interpersonal problems. These two dimensions are called the need for power and the need for relationship and are understood to be at right angles to one another (orthogonal), just like the X and Y axes on a graph. On the vertical Y axis is the need-for-power dimension ranging from high need-for-power (dominance) to low need-for-power (submission). On the X axis is the need-for-relationship dimension ranging from high need for relationship (affiliation) to low need for relationship (detachment).
Most of the personality disorders can be placed into one of the four quadrants that are created by the intersecting lines of these X and Y axes. Some personality disorders, such as the Borderline Disorder, are considered to bounce back and forth between two quadrants (see diagram A). In contrast, healthy personalities exhibit a full range of interpersonal approaches and will generally adjust their manner of relating to others based on the person, the type of relationship, the situation, and the circumstances. Thus, they can comfortably interact in each of the four quadrants and modify their interpersonal style as needed. For instance, it's probably best to interact on the slightly deferential, submissive side of things when we interact with our boss, but probably best to operate on the more dominant side when parenting our children. Once again we see that healthy personalities are distinguished by flexibility; in this case, interpersonal flexibility.