Janette Oke 
Love Takes Wing (Love Comes Softly Book #7) 

Book 7 of the bestselling Love Comes Softly series. Belinda Davis had trained as a nurse to assist her older brother, Doctor Luke. But as time goes by and she sees those she’s grown up with getting married and settling into their own lives, Belinda becomes restless. What had seemed exciting and fresh becomes dull and routine. When she meets an elderly woman who needs nursing care, Belinda jumps at the invitation to go to Boston–a large, "civilized" city with cultural opportunities she’s never even dreamed of in her little prairie town. But in spite of financial security and countless new experiences, Belinda finds herself restless, lonely, and empty inside.