Answer by taking a quote from the following article:

Marie Charlotte Carmichael Stopes (15 October 1880 - 2 October 1958) was a British author, palaeobotanist and campaigner for eugenics and women's rights. She made significant contributions to plant palaeontology and coal classification, and was the first female academic on the faculty of the University of Manchester. With her second husband, Humphrey Verdon Roe, Stopes founded the first birth control clinic in Britain. Stopes edited the newsletter Birth Control News, which gave explicit practical advice.

Around the start of her divorce proceedings in 1913, Stopes began to write a book about the way she thought marriage should work. In July 1913, she met Margaret Sanger, who had just given a talk on birth control at a Fabian Society meeting. Stopes showed Sanger her writings and sought her advice about a chapter on contraception. Stopes' book was finished by the end of 1913. She offered it to Blackie and Son, who declined. Several publishers refused the book because they thought it too controversial. When Binnie Dunlop, secretary of the Malthusian League, introduced her to Humphrey Verdon Roe--Stopes' future second husband--in 1917, she received the boost that helped her publish her book. Roe was a philanthropist interested in birth control; he paid Fifield & Co. to publish the work. The book was an instant success, requiring five editions in the first year, and elevated Stopes to national prominence.  Married Love was published on 26 March 1918; that day, Stopes was visiting Humphrey Roe, who had just returned with a broken ankle from service during the First World War after his aeroplane crashed. Less than two months later they were married and Stopes had her first opportunity to practise what she preached in her book. The success of Married Love encouraged Stopes to provide a follow-up; the already written Wise Parenthood: a Book for Married People, a manual on birth control that was published later that year. Many readers wrote to Stopes for personal advice, which she energetically endeavoured to give.  The following year, Stopes published A Letter to Working Mothers on how to have healthy children and avoid weakening pregnancies, a condensed version of Wise Parenthood aimed at the poor. It was a 16-page pamphlet and was to be distributed free of charge. Stopes's intended audience had--until this work--been the middle classes. She had shown little interest in, or respect for, the working classes; the Letter was aimed at redressing her bias.  On 16 July 1919, Stopes--pregnant and a month overdue--entered a nursing home. Stopes and the doctors clashed over the method of birth--she was not allowed to give birth on her knees. The child was stillborn; the doctors suggested the incident was due to syphilis, but an examination excluded the possibility. Stopes was furious and said her baby had been murdered. She was 38 years old.

What is married love?
Stopes began to write a book about the way she thought marriage should work.