On the surface, the man I was dating seemed to have it all. A good job working high up in the government; an Italian millionaire who was also qualified in law; a boat driver’s license. As relationships go, it was panning out to be an exciting one. But there was one caveat. None of it turned out to be true.

Instead, I came to realise I’d had an eleven-month relationship with someone who was truly delusional. Through a web of lies, coercion and manipulation, he had lured me into his carefully curated false reality – a process which went back years in his history, against a backdrop of severe mental illness characterised by anxiety, emotional dysregulation, and pathological lying. I was unlucky enough to fall for it.

The fact that I work as a practising psychologist makes my gullibility even more astonishing. Every day, I’m tasked with understanding people and how they function in the world. If I can fall for his pathological lies, then what chance does the next person have?

When we first met, he kept details about himself quite vague. As he learnt more about me, he curated a reality and a version of himself that would most attract my interest and gain my empathy. This is part of pathological lying – delivering lies that are beguiling or dazzling to the listener. Since I was training to be a Counselling Psychologist, he told me he saw a therapist weekly because he had been exposed to atrocities at work. This man had done his homework. He studied the language and concepts of therapy and delivered them to me with fluency and composure. He confided in me, revealing MI5 ‘secrets’ – devasting and emotionally potent secrets about war and terror attacks. Or so I thought. The facts about the incidents always turned out to be accurate when I later heard about them on the news. Most likely he had tuned into CNN a few hours before I woke up, to appear in the know and seem one step ahead.

He also used his legal skills to act as my rescuer. I had a dispute over the return of a deposit on a flat I was renting. Due to his knowledge of the law, he made a few calls and within the day the money was in my account. He informed me of the basis of the law and my rights, and said he used these facts to respectfully educate the landlord. I should have looked more deeply into his actual approach when I received a text from my landlord saying, ‘there was no need to set your guard dog on me’. But I didn’t want to see it at the time. I desperately wanted to stay in the fantasy of the relationship.

My delusional date habitually flooded me with spontaneous surprises, gifts, and expensive outings, as though money were no object. But he side-stepped or responded with angry avoidance when I asked why he hadn’t fixed his severely cracked iPhone screen months after dropping it, and why he had chosen not to move out of shared accommodation since he had the money and was now in his late thirties.

I use the term ‘isolated vacuum’ to describe the relationship because he did his best to avoid any social gatherings or interaction with my friends, blaming his reluctance on his crippling social anxiety. He discouraged me from speaking with my friends about him, saying it was a betrayal of his trust. This meant the sounding board my friends could have offered wasn’t unavailable. He could not avoid the odd encounter with my family though, and that’s when I really saw the showman. He dazzled, dripping with charisma, and made each of my relatives he spoke to feel like the only person in the world.

Social events like this would exhaust him. He was always drained and tired afterwards. Being someone else as your baseline, then having to socially perform on top of it, must have been exhausting. He began to need breaks from keeping up the persona to me too. After holidays he needed downtime and space, so he could switch off. Then came the fake trips – I imagine exhaustion was also the reason for these. Last minute trips would spring up — Paris, Madrid, Brussels — and I would receive pictures of every meal he was apparently snatching in between long working hours. These were photos of his plate, the fancy ceilings and décor of the restaurants he ate in, but never a picture with him in it.

Soon, the cracks began to show. I could see him becoming more anxious. He was restless, unable to sleep, agitated, his routine becoming more rigid with structure and excessive exercise. I imagine he was struggling to keep on top of the lies and manage the constant performance. He grew irritable and couldn’t stand my questions anymore, even the innocuous ones, and he sometimes seemed confused, becoming angry and more explosive.

The tugging in my gut was growing, and I knew something was ‘off’. I wanted to ignore it but now there was an element of fear as well as doubt, and even a sense of danger. My internal voice started to ask whether I could trust this man. I pushed on with the questions and the bluffing, before confronting him over drinks one night.

I was aware the questions would push him over the edge. Subconsciously, I knew we needed to go there for it to be over. He crumbled and it all fell apart. He told me it had all been a lie. He admitted he never went on any of the trips. Instead, he hid for days at a time in his room, alone in his shared flat, sending me pictures of restaurants and plates of food he’d found searching the internet. I was utterly gobsmacked.

We all suffer the occasional minor delusions or misperceptions, such as being certain a leaf is an animal, or a coat stand in the corner of a dark room is an axe wielding murderer. But once we reality test, and our first impression seems unlikely, we can easily discern what is truth and what is fiction. Similarly, research looking at trait identification with fictional characters shows we are all capable of powerfully identifying with characters in films. When we feel a connection to a character on screen, it activates the part of our brain associated with thinking about the self, and this may lead us to start adopting some of the character’s traits. But we are then able to switch back to our normal selves when we go home and return to our usual roles.

The difference with the man I was dating is that he over identified with a persona to gain rewards and positive reinforcement from the world, to have his emotional needs met, to feel praise, recognition, and admiration. This probably started out being quite harmless, pretending that he’d done better on a test at school than he had or telling his friends that his family owned a yacht instead of a speedboat. As this trait became more and more rewarding, the false narratives engulfed him. Over time he became well practised in knowing how to tailor each falsehood to the personality of the person in front of him, and sensing what persona would most impress them.

When I found out the truth I was stunned, but I also felt some relief, as though I had finally scratched an itch that had been bothering me for some time. I could see the shift in him too. The stress seemed to drain out of him as he gave into the tiredness. It was as if someone had released the rope that had been holding him up. That’s not to say his delusion of grandeur left him entirely. As we said our farewells, he told me he had started medical school and maybe our paths would cross again. He was already building his next story, his future self, ready for the next person.

Just About Coping: A Real-Life Drama from the Psychotherapists Chair by Dr Natalie Cawley (Pan Macmillan, £16.99) is available now.

Dr Natalie Cawley is a psychotherapist and counselling psychologist with an BSc, MSc and PsychD in psychology and has worked and trained in both the NHS and private practice, within paediatric and adult services. Her experience covers a wide range of health conditions and clinical presentations in the community and within psychiatric hospitals.