I blame Dorothy Sayers

Imagine a man--not a terribly honorable man (guilty, in fact, of murder; though only two people know it yet)--who has become entangled in a deadly drug-smuggling ring. At the beginning, he didn't know what he was getting into, but he needed money; and even when he did find out what it was all about, he stuck with it. Imagine that such a man, under the growing suspicion that you (who are obviously a British lord who moonlights as a self-directed private detective of sorts) are on to his trick, comes to your flat one night to confess. After exchanging tales and getting the whole thing sorted out, making it quite evident that his game is up, suppose the man confides that, though he himself is strangely relieved that it's over, his one great distress is that his past deeds will cause his wife and child such pain and public disgrace.
The role the man played in the drug-trafficking was inconspicuous, though vital. Its revelation, besides shocking and shaming his family, would also ruin the reputation of the advertising firm for which he worked, and through which he secretly worked his mischief.
The murder he committed was related to the drug business, and was rather ingeniously constructed to look like an unfortunate accident, and has been credited as such by all the world, apart from yourself and one discerning young lady.
Suppose you are well aware, as you talk together this evening, that another member of the drug ring has trailed your man here, and is waiting somewhere in the shadows outside, fully intent on doing him in as he makes his way home again.
You are also aware that if your man stays a few hours in your flat, he will be safe, for your friends at Scotland Yard will by then have sprung their trap on the rest of the gang elsewhere in the city, and the would-be assassin will have fled for his own life.
The man contemplates suicide, to save his wife and child from the scandal (provided you hold your tongue, of course).

Knowing all this, could it be justifiable to suggest something else to the man? What if you said,

"Listen! I think there is one other way out. It won't help you, but it may make all the difference to your wife and child."
"How?"
"They need never know anything about all this. Nothing. Nobody need ever know anything, if you do as I tell you."
"What do you mean? Tell me quickly. I'll do anything."
"It won't save you."
"That doesn't matter. Tell me."
"Go home now. Go on foot, and not too fast. And don't look behind you."

What if the blood drained from his face as he said, "I think I know what you mean. . .very well."

And what if he did it?