A search of the research literature turns up zero information on the connection between borderline personality and cheating. But, many spouses and partners of people with borderline personality (BPD) relate stories of their BPD partner engaging in infidelity. Is it true that people with BPD are more likely to cheat?
While there isn't any hard data, there are some reasons to expect that people with BPD may be more prone to infidelity in their relationships. Two of the key features of borderline personality are problems in relationships and problems with impulsive behavior.
People with BPD often have an intense need to feel loved and accepted, along with a lot of ups and downs in their relationships. And, when they are feeling abandoned or rejected, they may engage in impulsive or risky behaviors. This means that they might do things without considering the consequences of their actions, just to "feel better" in the short term. Certainly, infidelity could fall into this category.
Does this mean that every person with BPD is at risk of engaging in infidelity? Absolutely not. Borderline personality comes in many different shapes and sizes; some people with BPD don't engage in impulsive behaviors, or their impulsive behaviors take other forms. However, there may be a subset of people with BPD who are at risk of cheating on their spouse or partner.
American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 4th ed, text revision. Washington, DC, Author, 2000.