Love, according to the veteran clinical psychologist Frank Tallis, is not lovely at all. Mostly it seems to involve loitering in public places, worried that your ex has reported you to the police. Alternatively it means getting rid of your partner so that you can masturbate at leisure because, let’s face it, you’re so much more fanciable than he is. Or it means frittering away a fortune on 3,000 prostitutes, by romancing them with candle-lit dinners and expensive jewellery, because you crave the drama of constant courtship.

Anyone who has ever fallen in love will have experienced all the symptoms of full-blown psychiatric madness: the disinhibition, the magical thinking, the OCD-ish tendency to check your messages (and worse still, your partner’s messages) every five seconds. The ancients called the condition “love-sickness” and Tallis suggests that we think seriously about reviving the term as a diagnosis rather than continuing to use it as a quaint metaphor. Certainly it trips off the tongue more sweetly than “Bereavement Hallucinatory Experience”, “Delusional Disorder: Jealous Type”, or even LLS (Looks Like Shit), which is apparently what shrinks write on your notes when you turn up at their consulting room with a broken heart.

Tallis explains that during the first three to four years of a relationship it makes evolutionary sense to be knocked silly by love. Nature needs us to be around long enough for any putative children to have a decent chance of survival. After that, the blissful feelings start to thin and we either whip up a new frenzy with a delicious stranger, or else settle for a conversation with our current partner about whose turn it is to put out the bins. Some poor souls, though, get stuck in the crazy stage, and it’s Tallis’s encounters with these desperately unhappy patients that provide the substance of this book.

There’s the mousy middle-aged woman who has fallen in love with her dentist and is convinced the feelings are reciprocated, despite the fact that he has moved his family to Dubai to escape her attentions. Perhaps the saddest instance is the man unable to go on holiday with his best friends because he has developed an intense romantic attraction to their six-year-old daughter, which he knows is terribly wrong. And most surprising is the elderly working-class widow who reveals to Tallis that her depression is the result not of losing a husband whom she loved, but a husband who was, improbably, as rampant as she was when it came to sex.

Tallis’s theoretical orientation is eclectic, which means that he provides a survey rather than a deep dive into the various ways in which a therapist might begin to understand and manage love-sickness. Sigmund Freud and Josef Breuer’s celebrated case history of Anna O rubs shoulders with Jacques Lacan and his mirror stage, which in turn abuts Melanie Klein’s good breast/bad breast, which sits alongside the mechanistic approach of cognitive behavioural therapy. (The last of these is especially good for the compulsive message-checkers among us.)

Yet while Tallis’s writing may lack the intellectual depth and poetic fluency of Adam Phillips or Darian Leader, it makes up for it with some riotous local colour. Take the distinguished physiologist colleague who injects his penis with an impotence cure and encourages conference delegates to admire his sturdy erection. Or the psychiatrist who confides that his clinical judgments are informed by his Chinese spirit guide, or the registrar who is now a protesting patient on the psychiatric ward that he used to run. Finally there’s the disconcerting revelation that couples therapy was invented by the Nazis.

Tallis has cherry-picked these anecdotes from a career that has spanned several decades, with the result that much of The Incurable Romantic feels curiously suspended in time. No one in these pages sends an email or even a fax; pornography can be accessed only by sidling into a newsagent; and a colleague turns out to have spent his childhood in a Nazi concentration camp. There is nothing wrong with this, but it does sit oddly with the verbatim accounts of therapeutic encounters that form the core of Tallis’s narrative. Perhaps he habitually used a cassette recorder to tape his clinical sessions – it would certainly add to the period charm of the piece – but, if that is the case, surely we should be told? As it is, and given that Tallis has a lively sideline as a commercial novelist, it’s impossible not to wonder whether everything – or rather, everyone – in this book is a composite, tacked together from bits and pieces of other people’s anguish. The result is a piece of work that comes off as curiously generic, as if written in response to the current publishing boom for medical professionals to open their casebooks as a means of pursuing life’s big questions.

• The Incurable Romantic is published by Little, Brown. To order a copy for £16.14 (RRP £18.99) go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.