Doctor in petticoats / Mary Connealy.

Enhanced descriptions from Syndetics:

When nurse Beth McClellen survives a stagecoach accident, she soon realizes the derelict traveling alongside her is a doctor, and she forces him to help tend the injured. Alex Buchanan, army deserter, finds he can only care for the patients as long as Beth is right by him - yelling at him! Beth thinks he's a lunatic when he proposes that they marry and work together in her hometown. There's no denying his skill, and Beth can see that he's emotionally invested in his patients. And there's the fact that he saved her sister. Though misgivings abound, Beth agrees. And that's when the real trouble begins. There's a murderous bounty hunter on Alex's trail. If Alex lives long enough, he can turn himself in - and perhaps face a firing squad. Not exactly the honeymoon of Beth's dreams. Can Alex find the faith he lost while surrounded by the horrors of war? And will doing the right thing by facing his past cost him his wife - and perhaps even his life?