The Waterfall by Margaret Drabble
Poet Jane Gray, whose husband has left her shortly before the birth of their second child, falls passionately in love with James, the husband of Lucy - Jane's cousin and her friend. Their adulterous affair remains secret until a tragic accident exposes it to the world and they have to face the consequences! The Waterfall is a powerfull novel about sexual awakening and obsession - and the violent conflicts of maternal and sexual love.