Most of us have been there: a relationship ends—one that, by any rational measure, needed to end—and yet you find yourself replaying memories, checking their social media, or wishing things had turned out differently. That disconnect between what you know and what you feel can be genuinely distressing, but understanding why it happens might help make it a lot less confusing.
The truth is, missing someone who hurt you isn't a character flaw or a sign of weakness. It's a deeply human response rooted in psychology, neuroscience, and the way we form attachments. Once you understand the mechanics behind it, you can start to separate what your brain is telling you from what you actually need, and that distinction matters more than most people realize.
Your Brain Gets Addicted to the Highs and Lows
One of the most significant reasons you miss someone who was bad for you is the neurochemical experience of being in that relationship. When you bond with a partner, your brain releases dopamine and oxytocin: chemicals associated with pleasure, reward, and attachment. In a stable, healthy relationship, these chemicals reinforce trust and security over time. In a toxic one, however, the pattern works very differently.
Dopamine actually flows more readily when reward patterns are intermittent, rather than consistent. This means the hot-and-cold dynamic of a chaotic relationship actually deepens your attachment rather than diminishing it; every rare moment of kindness hits harder precisely because it was unpredictable, and your brain was trained to chase it.
The brain's chemistry is also altered during cycles of conflict and reconciliation: stress hormones released during painful episodes, followed by dopamine during calmer periods, create a potent mix that can make the relationship feel genuinely addictive, as odd as it might sound. So when the relationship ends, what you're experiencing isn't just emotional grief, but also a kind of withdrawal, which helps explain why the longing can feel so physical and overwhelming.
You're Grieving a Version of Them That May Not Have Been Real
Another layer of this experience is that you're often not missing the person as they actually were—you're missing who you believed they could be, or who they were during the rare moments they showed up well. This is one of the more painful distinctions to sit with, because it means the loss you're feeling is partly for something that was never fully real.
Intermittent reinforcement of a reward—the other person's occasional love and kindness—amidst otherwise harmful treatment becomes what you hold on to, and you can end up formulating your sense of identity around winning their approval or waiting for them to change. When that person is gone, those parts of yourself are suddenly unmoored, and that destabilization can register as longing even when what you're really feeling is a loss of self.
There's also the matter of cognitive dissonance: it describes the discomfort of holding two conflicting beliefs at once, and in this case, recognizing that someone was both abusive and caring. To resolve that inner tension, you try to excuse their bad behavior, and letting go of the relationship means stopping that mental calculus, which isn't easy when the brain has spent so much time trying to make sense of the contradiction.
Early Attachment Patterns Play a Bigger Role Than You'd Think
It would be overly simplistic to attribute missing a harmful person entirely to what happened in that specific relationship. For many people, the pull toward, and grief over, someone who hurt them connects to patterns established much earlier in life; how we learned to attach to caregivers shapes what feels familiar, and familiarity has a powerful influence on what we interpret as love.
Children of dismissive or cruel caregivers, for example, can develop insecure attachments; inconsistencies in reward and punishment highlight the affection they do receive, forcing a split between the harm and the kindness such that the child forms an overall positive view of the caregiver and focuses primarily on the affection. When that becomes your template for closeness, you may unconsciously seek out relationships that replicate it, and feel its absence acutely when it's gone. Furthermore, a person who carries a history of insecure attachment or early trauma already has a nervous system calibrated to threat, which can make the bond feel even more intense. That means the pain of abandonment may feel more dangerous than the harm itself.
It's also worth noting that this doesn't mean something is fundamentally wrong with you. Missing someone who wasn't good for you is one of the more bewildering parts of being human, but the longing you feel says more about how your brain processes attachment and loss than it does about the quality of the relationship itself. With time, support, and sometimes professional help, it becomes possible to grieve honestly, understand what you're really missing, and build a clearer sense of what you actually deserve.
