Grace Livingston Hill 
The Measure of a Man [EPUB ebook] 

Janet Grayson and Harley Bruce grew up as playmates in the small village of Springdale. Their bond remained strong until Harley left for college; but after several years in Europe, Harley has finally returned home, and he has brought with him a loud, thoughtless group friends.
It’s up to Janet to remind Harley that he has a higher calling than merely seeking a good time with his friends from town. If only she can get him to attend church, and maybe even teach the boys in his old Sunday-school class, she’s certain she can remind Harley of principles by which he once lived.
But there are many people vying for control of Harley Bruce, and Janet can only pray for the strength she’ll need to help her friend regain his faith in God.