How do I know if he's the one? Is there a seven-year itch? Do chat up lines work and, if so, which ones? There is academic research out there that can answer these questions: Dr Luisa Dillner, author of the Guardian column 'Love by Numbers', has sifted through it to give you the facts about flirting, dating, marrying, cheating and much more...

"Her fascinating findings throw a new light on the dilemmas of dating, marriage and romance" Daily Mail "Absolutely not your typical self-help book. Luisa burrows into the research, emerges triumphantly bearing aloft the relevant statistics, then uses them to provide advice that is useful, yet delightfully written. Read this book for interest, read it for entertainment, read it to throw light on any question you might want to ask about relationships" - Susan Quilliam

Dr Luisa Dillner is a doctor and a publishing director at the British Medical Journal Publishing Group. Published by the Guardian, the Observer, Cosmopolitan, Vogue and Elle, she has also written for the famous Mumsnet website where her letters for mothers have been sent out for seven years. She has four children, lives in London and most importantly has a perfect long term relationship...