Broken Country by Clare Leslie Hall

 This is the story of a woman, Beth, who loves 2 men. Rich and handsome Gabriel is her first love. Frank, a salt of the earth sheep farmer, is the man she marries. And the lives of the three of them will always be intertwined. 

The main action is set in rural England in 1968. There are frequently flashbacks to "before" though we don't know exactly before what. It's an engrossing book about love and loyalty, with some tragedy thrown in.