Kristin Billerbeck 
Meet My Sister Tess [EPUB ebook] 

Clark is everything Tess Ellison thinks she wants in a husband. He is stable, a good provider, the kind of man who can allow Tess to fulfill her mothers dying wish: that her mentally-handicapped brother, Robby, will never be put into an institution. Robby loves to introduce his sister to every new person he meets, including Greg Wheaton, the new social worker in town. It is obvious that Robby is encouraging Tess and Greg to become friends. Soon Tess is forced to admit a marriage of amiable partenership may not be for her. Can she trust God to keep her mothers dying wish and give her the man she loves?