The thing that fascinates Harry about Charlotte is that she is pure, innocent and untouched. But that what she wants everyone to think.
When people hear Charlottes name, they think of how she is such a sweet girl and that her youth, despite being 17 hasn't been corrupted and stuck with religion. Luckily for Charlotte her licentiousness has not been exposed and hardly anyone could imagine her with her lips wrapped around anything but a lollypop.
Harry had retired early at age 25, with enough money to be set for life, but his mental state was what caused him to quit the job which caused the stress and strain. Harry found his saviour at church, and it wasn't in god but Charlotte herself.