In all romantic relationships, the VTA is activated, in the same way as doing drugs. That’s why love feels like such a rush, and why getting ghosted can feel like a brutal cold turkey approach to withdrawal. But here’s the thing: it’s the toxic, unstable, emotionally confusing relationships that trigger the cycle of dopamine chasing particularly hard.

“Relationships that work like slot machines for validation are often addictive,” notes Dr Anna Lembke, a psychiatrist, chief of the Stanford Addiction Medical Dual Diagnosis Clinic and author of Dopamine Nation. “That is to say, when relationships are chaotic, unstable, volatile and unpredictable, certain personalities will be attracted to the pattern of intermittent reinforcement that can drive compulsive engagement.”

Gambling is a helpful analogy to understand this. A large part of what’s so addictive about gambling is that you only sometimes win. Each time you lose, that low makes you want to chase a high to make up for it. An unstable relationship works in much the same way – to experience longing, wanting or intense desire, you can’t have easy, constant access to it. Each time you don’t get that win when you gamble, your desire for the win increases. Each time the person you love doesn’t return your affections in the way you crave, you become even more desperate.

“It’s the yo-yo, the back and forth and back and forth,” Fisher explains. “When they’re gone, you miss them terribly. Then they come back and the dopamine has shot up again – you’ve got hope that it might lead to something this time, so you give it a chance. Then they don’t come home, or they call you by a different name, or there’s some other indication that it’s not working, and you get mad and they leave, and you miss them terribly again.”

A healthy relationship can feel boring in comparison. When you’re in a long-term, committed relationship with someone you love and who returns your love in a predictable way, there aren’t those same crashing highs and lows. If you’re the type of person who is drawn to that dynamic, it can be incredibly difficult to resist the lure of an addictive, unhealthy relationship and instead find fulfilment in a more consistent one.

What makes you ‘that type of person’? It’s complex. Scientists are still working to understand what makes someone more prone to addiction, and the reality is that multiple factors – the environment in which you were raised, genetics, a chemical imbalance in the brain – are likely to blame for why one person can use a substance without becoming addicted while another will be immediately hooked. In the world of love addiction, research is ongoing. But what we do know is that our chasing of unstable relationships is at least in part caused by our previous relationships, including those with our parents.

“If our caregiver wasn’t consistently responsive to our needs, we will form an anxious attachment style, which manifests low self-esteem, feeling unworthy of love and a fear of abandonment,” says relationship psychologist Dr Limor Gottlieb. “In adult relationships this pattern continues in the form of excessive reassurance-seeking and closeness to our partner. If a caregiver was neglectful of our needs, we will develop an avoidant attachment style characterized by independence and self-reliance. In adult relationships, this looks like fear of intimacy and seeking space from partners.

“The paradox is that often partners with these opposing attachment needs attract each other because they exacerbate each other’s attachment fears.”

Toxic relationships can be genuinely addictive – that’s why they’re so difficult to get over