Obligated by faith, upheld by general morality, I should think. But when I can't coast by on an assumption of good morals due to my position, I thought the reassurance of my obligations would help here!

Mind you, where I come from, there are people more qualified to help people through their troubles on a psychological level and they're also required to uphold confidentiality, so I suppose it's just something that people desire when it comes to their deepest secrets, no matter who they tell.