Who's kept something secret from someone for the other persons sake? not talking about affairs or anything like that but stuff that they are better off not knowing about.
Mine was I never told my wife I found a dead and decomposing slug stuck in our kettle once. It was hidden away in the spout and I only found it when cleaning it one day. It made me wretch when i found it. Luckily I don't drink that many hot drinks but my wife who hates slugs would have freaked out if I'd told her.