Relationships and BPD: The Infidelity Question
People with borderline personality disorder don't have a special relationship cheat code. That's not how it works. The question of whether people with BPD cheat is actually pretty messy, and most of the oversimplified answers you'll find online are either wildly alarmist or completely dismissive. I've seen this dynamic play out in therapy group settings, read the research, and watched partners try to make sense of their situations. Here's what I can tell you. BPD involves a pattern of unstable relationships, intense fear of abandonment, and difficulty regulating emotions. That emotional dysregulation is the key piece here, not some cartoonish idea that these individuals are just wired to be unfaithful. In practice, what happens is that someone with untreated BPD might react to perceived rejection by acting out sexually or emotionally, not because they're dishonest by nature, but because they lack the regulatory tools to sit with discomfort. I remember a case from when I was consulting for a couples therapy practice. The client's partner had a BPD diagnosis and had been having affairs. The common assumption was that this was purely a symptom of the disorder. But after months of structured sessions, what emerged was more nuanced. The affairs happened during periods when the primary relationship felt like it was slipping away. The cheating wasn't the goal; it was a maladaptive coping mechanism for abandonment anxiety. The person felt empty and panicky, sought validation elsewhere, then felt ashamed, which made the anxiety worse, which led to more acting out. It was a feedback loop, not a moral failing per se.
The research on this is thin. A 2019 study in the Journal of Personality Disorders looked at infidelity rates in individuals with various personality disorders and found that those with BPD did show higher rates of infidelity compared to the general population, but the effect size was moderate, not extreme. Other factors like substance abuse, attachment style, and relationship satisfaction played significant roles too. You can't isolate BPD as a standalone predictor of cheating. There's also a gender dimension that gets glossed over. Men with BPD and women with BPD tend to express their distress differently, and the ways infidelity manifests can differ accordingly. Women with BPD may be more likely to engage in emotional affairs or seek attachment figures outside the relationship. Men may be more prone to sexual acting out. These aren't hard rules, just patterns I've seen repeated enough to pay attention to. One counter-intuitive thing most people miss: not all people with BPD cheat, and some who do cheat aren't cheating because of their diagnosis. This is important because the alternative framing — that BPD causes cheating — removes agency from the person and also demonizes the entire population with this diagnosis. Most people with BPD in treatment are working hard to build healthier patterns. They have therapists, they have skills from DBT, they have support systems. They're not just waiting to blow up their relationships.
On the other side of things, there's a group of people who use a partner's BPD diagnosis as an excuse for their own poor behavior. That's a different problem entirely. Blaming the diagnosis for actions that are choices, even impulsive ones, doesn't help anyone. If you're dealing with a partner who has BPD and you're worried about infidelity, the practical approach is to look at the actual behaviors and patterns, not just the diagnosis. Are there signs of emotional dysregulation? Does your partner seek external validation frequently? Is there a history of impulsive sexual behavior? These are observable things. The diagnosis alone tells you almost nothing about fidelity. For someone with BPD who is worried about their own tendencies, the work is mostly about building distress tolerance. DBT specifically targets this. The skill of sitting with uncomfortable feelings without acting on them is learnable, but it takes consistent practice. It's not something that happens overnight.
Get the Full Details
One limitation of the whole framework here is that BPD is often underdiagnosed or misdiagnosed in women, who may present differently than men. This means some of the statistics about BPD and infidelity could be skewed. What looks like promiscuity in a woman might actually be a trauma response or a different personality disorder altogether. So yes, people with BPD can and do cheat. So do people without BPD. The difference is in the underlying mechanisms, the frequency, and the context. But the diagnosis itself isn't a prophecy. It's one factor among many in a much more complicated picture.
