Is it always wrong to violate a confidence?

A friend asked me whether it's always wrong to violate a confidence. Sharing a confidence involves a two-way trust. It carries the implicit condition that the individual sharing a confidence not abuse the trust or take advantage of the person he confides in. 

There's a prima facie obligation not to divulge information shared in confidence. But that's not absolute. For one thing, you don't know in advance what someone will confide in you, so you can't render informed consent to keep it secret. A person can't unilaterally obligate you to keep their secret. They don't have that coercive moral authority over you. You can't reasonably be expected to make a commitment when you're in the dark. Indeed, open-ended commitments can be unethical. 

There may be other the concerned parties who also have rights. Keeping a secret may unjustly harm them. So we have to balance competing duties. In case of conflict, some duties override other duties. 

To take a hypothetical case, suppose I know the pastor's son is a closet homosexual. I suspect that, and at some point he confides in me.

Normally I'd protect his identity. I'd cover for him (without lying), because he has a struggle, and he needs a straight friend to talk to, where he's free to let down his guard. To out him would be gratuitously harmful to his reputation and his faith. 

If, however, he decides to follow his dad's career path by going into the family business, as a youth pastor (say), that changes things. Now he's inserting himself into a situation which will, at the very least, expose him to unnecessary temptation, and at the worst he's deliberately exploiting the situation to seduce vulnerable young men. At that point, all bets are off. 

Minimally, I'd warn him to stay clear of Christian ministry and other venues where he works with other young men. I'll also tell him that if he doesn't heed the warning, I will be obligated to out him for the protection of the innocent. At that point he forced my hand. 

Just to clarify, there are situations in which I'd lie for someone to cover for them, but in the hypothetical situation I raised, I don't owe him that. All other things being equal, I'm prepared to cover for him short of lying for him. There's a difference between concealing and deceiving. Sometimes both are justified, but sometimes concealing is justified while deceiving is not. 

Suppose I know a classmate cheated on an exam. Suppose he knows I know. But he's now remorseful about his action. 

I'm not going to rat him out, in part because I'm not personally responsible for what he did, and he's contrite about his wrongdoing. At this stage it would be more harmful to rat him out. In that sense I'll cover for him. I'd keep it between us. 

If, however, his action was exposed by someone else, I'm not going to lie for him. He did wrong. It's not my duty to lie to coverup his wrongdoing. He can't reasonable expect that from me. Having taken a risk, he must be prepared to face the consequences.