Grace Livingston Hill 
The Man of the Desert 

Fleeing the unwanted attentions of an aggressive suitor, wealthy and beautiful Hazel Radcliffe becomes hopelessly lost in the Arizona desert. Weak and weary, she falls unconscious from her horse. Soon Hazel is found by John Brownleigh, a handsome missionary who lives in the desert. As he carefully nurses Hazel back to health, a strong and true love begins to grow between them. But John, poor and humble, knows he is not of Hazel’s world, so he does not speak of his love. And because Hazel feels strongly unworthy of John and his work, she, too, remains silent. And so they part, without acknowledging the love between them.
Back home among her family and friends, Hazel makes a startling decision: she will do all she can to change and become deserving of John’s love. But can she do so before it’s too late?