• Why we Fight by Kim Polinder (HarperOne £22, 256pp)

Do you fight with your partner? About the bins perhaps, or the washing up?

Whatever the superficial graze that manifests in a row, it starts, says psychologist Kim Polinder, in much deeper wounds.

We fight, she says, because those core wounds are hurt again and again by something we feel deep within – like the press of a bruise, or the reopening of a cut.

Our fighting isn’t really about putting out the recycling or who last did the washing up; it’s about something old and sore.

Kim Polinder: psychologist and therapist

Conflict triggers past trauma, causing people to assume entrenched emotional roles rather than being their ‘true selves’. To understand why we fight, and to resolve those fights, Polinder argues we need to understand our triggers – and that means understanding our trauma, because when we fight, ‘we’re reacting to every moment in our past where we were being treated in the same way’.

It’s why a throwaway comment or small slight from a partner or friend can send you into a spiral, ‘and why they seem just as confused as you are about why it upset you so much’.

Polinder has an interesting backstory. At five months old, she was left on a path in rural South Korea and found by a passerby. She was first taken to the police station, then to the children’s hospital, and later placed in a foster home before being adopted by an American family.

As an adult, she pursued a successful career in tech as an IT engineer at a Fortune 500 company. She was drawn to technology because ‘computers made sense to me in a way that people didn’t’. IT was ‘predictable, logical, and I didn’t have to sit around managing other people’s burdensome feelings’.

Later, she qualified as a relationship coach and therapist, when it became apparent to her that ‘conflict feels like a severity 1 system failure’.

It is Polinder’s early life experience that shapes her empathy with clients: ‘Out of this early separation wound of being given up by my birth mother, my abandonment issues were born’.

She describes this as a ‘core wound,’ which she defines as ‘an old emotional injury that sticks with you’, whether from a single experience or a repeated pattern of rejection or emotional neglect.

A ‘core wound,’ lingers as ‘an old emotional injury that sticks with you’

But it is her career experience that shapes her approach to healing these old wounds. In the tech world ‘we had flowcharts to guide us through the troubleshooting process . . . a series of yes-or-no questions that led to a logical pathway forward. If A happens, go to step B. If not, go to step C.’ Those charts gave IT engineers a way to move forward ‘through a system failure without getting lost in the weeds’.

If Polinder’s original wound was the abandonment by her birth mother, it was deepened when her parents adopted a second daughter from South Korea.

S he says: ‘That’s when my anger intensified. I have vivid memories of hitting her as a stubborn child, trying to control her whenever I didn’t get my way. In those tantrums, I felt strong for a second, then ashamed for days. Control felt better to me than closeness.’

It wasn’t until decades later, she writes, that she understood the ways she’d reacted to her sister’s arrival: ‘I had been projecting my own self-hatred about being Asian onto her. I still remember the shock of seeing my first-grade class photo and realising how different I looked from all my blond-haired, blue-eyed classmates. My math equation started forming: blend in to avoid being different.’

That equation results in what she calls ‘bad maths’ – trying to make things add up, to make sense of the world, to cope. ‘We calculate which behaviours lead to pain and which ones bring reward,’ she says.

Polinder offers several examples of this ‘maths of lovability’: Mum is anxious + I make her laugh = I am responsible for my mother’s happiness. Dad ignores me + comments when I do well in sports = I am worthy when I am athletic. Mum yells at my rebellious brother + I stay obedient = I am lovable when I don’t cause problems.

It might be decades since your mother yelled at your rebellious brother – core wound – but the sum of the bad maths, ‘I am lovable when I don’t cause problems’, sustains.

One of the best ways to check whether your maths is off, she writes, is to ask: ‘Am I starting to feel resentful?’ Now ask yourself: how big a part does resentment play in rows about the bins, about the washing up?

G ive me a child until he is seven, so the saying goes – attributed variously to Jesuit brothers and Aristotle – and I will give you the man (or woman).

Think of childhood as wet clay, easily shaped. By seven, it’s moulded, dried, whatever pattern was stamped into its surface set fast. Core wounds and all.

Throughout the book, Polinder cites client case studies; readers may find their own rows mirrored in Maya and Devin, for example.

Growing up, Maya had a father who withdrew from emotion: ‘He would disappear for days, retreating into work or distractions, and Maya had learned that if she wasn’t constantly proving her worth, she would be ignored.’

When her partner Devin doesn’t respond to a text, her default is to feel the same rejection she felt when her father withdrew – ‘it felt like all the times she had been left behind before’ – and her reaction is out of all proportion. There’s a row.

Devin, meanwhile, grew up with a controlling, critical mother, so ‘when Maya demanded more from him emotionally, it felt like another way to be told he was failing’ – the basis for another fight.

We fight, Polinder writes, ‘because of how we learned to perceive danger, and as a result, how to protect ourselves. The number one job of the brain is to survive, and our triggered responses reflect our sense of danger.’

True to her engineering background, she unpacks the psychology in tech terms: ‘We can learn communication skills (install a new app), but conflict resolution ultimately boils down to a regulation problem, not a communication problem.’ She applies the same principles to her methods here: a systems- based, practical flowchart approach to conflict, built around two central prompts – ‘do I feel understood?’ and ‘find a solution’ – designed to ‘break a complex emotional rupture into clear, doable steps for repair’.

It’s a clever device, casting emotional dysfunction in the language of systems and bugs; Polinder’s own IT-to-therapy arc makes the metaphor feel lived-in rather than gimmicky.

What distinguishes Why We Fight is the case studies and the ‘bad maths’ framework, which give readers a genuinely useful concrete tool for catching themselves mid-row. I challenge you not to find some of yourself somewhere in this book.

It will press on the bruise of your own core wound – but it will also help you stop picking at the scab of it.