One Man's Mission (Chesterfield Colorado #4)
Deann Smallwood

And no matter how much his beloved mother coaxed, he would not consider staying in Chesterfield and becoming a country doctor. Never. Not even meeting McKenzie, or Mac as she preferred, would sway him. He would ignore the budding warmth in his heart whenever she was near.
Mac, an unwed mother, feared her reputation would sully the handsome doctor. The good townspeople would look down on him for associating with her. No, she could never allow her feelings to surface. Never could she give in to loving the kind and compassionate doctor.
Patrick was meant to be a surgeon not a country doctor. Mac was meant to live a life of shame. Were their circumstances insurmountable?