The Trespasser

The Trespasser is a 1912 novel by D. H. Lawrence. Set mostly on the Isle of Wight, it tells the story of Siegmund, a married man with children, and his adulterous affair with Helena.
Originally it was titled the Saga of Siegmund and drew upon the experiences of a friend of Lawrence, Helen Corke, and her adulterous relationship with a married man that ended with his suicide. Lawrence worked from Corke's diary, with her permission, but also urged her to publish; which she did in 1933 as Neutral Ground. (wikipedia.org)