Plain Promise by Beth Wiseman

Plain Promise is the story of Sadie Fisher, a young Amish widow who rents out her guest house to a single man from California.  Shortly thereafter, his autistic son is dropped off by his ex-wife, who then is killed shortly after she leaves in a car accident.  Kade hasn't spent any amount of time with his son and doesn't really know how to deal with his behavior.  Kade is a wealthy developer who,despite all of his toys is deeply unhappy.  Sadie begins to feel attracted to hi, but knows that being with him would mean leaving her family and friends.  To put a twist into the story Sadie has been corresponding with another Amish man in Texas for some time now and believed that he is the man for her until Kade came into the picture.  The story continues with Kade learning more about the Amish life from Jonah and elderly man in the community.  Sadie tries life in Texas for a while be realizes her life is back in her home town with her family and friends.