Coral Glynn by Peter Cameron is a novel just published by Farrar, Straus and Giroux.
It takes place in 1950 and is about a young nurse who has been engaged to look after a dying elderly woman living with her war wounded son and evil housekeeper in an isolated mansion in the English countryside. The woman dies and the nurse and son marry. Complications ensue, including a brutal child murder for which the nurse is a suspect. But Coral does marry happily. The book is Harlequin length at 210 pages.
So far so good, a Harlequin plot. Then there is the cover - an old-fashioned on canvas by hand painting. A young woman seemingly at risk in some mysterious way. Nothing 21st century about the painting.
But there are problems. The writing is better than, I'd venture a guess, any of the tens of thousands of books published by Harlequin. Then there is the explicit homosexual angle. So not a Harlequin.