Suspicious:  I suspect my long-time business partner of corrupting our venture's bylaws to give him lopsided gains from our joint efforts.  Confronting him might devastate our relation, but I have to know.  What should I do?

Business-Abby:  Give careful thought, please, to what you "have to" know.  Most who fear cheating are mistaken, and even if your bylaws are lopsided that could just be an honest mistake.  Even mentioning your suspicions to anyone might destroy your business, and could you really live with yourself if you destroyed your life's work, and betrayed employees, customers, and suppliers who rely on you?  If you wouldn't act on the info, why get it?  If you must do something, first consult with a lawyer about the consequences of even looking into this possibility. 

This would be odd business advice; I'd suggest first privately asking an accountant if your bylaws are lopsided.  Why get worked up over something you can cheaply check on?  But the above is pretty much what advice-columnist Carolyn Hax tells a man who suspects his wife's two year old daughter is not his:

Give careful thought, please, to what you "have to" know. When just seeking the truth could change your life in dramatic and irreversible ways, it's best to start not by actually doing something but by inviting each possible truth into your imagination as fact. … You need to … assume your wife did cheat … and then you need to decide whether you'd want to stay in the marriage or leave.

If the answer is to stay … then you need to ask yourself, is that outcome better served by not digging into the past? If the answer is to leave, are you ready to challenge your paternity — or have it challenged by your at-that-point-estranged wife? …  You can't entirely rule out the rarer than rare, yet not unprecedented, hospital error. …

If you decide you'd want this child no matter what, then the question becomes, again, why you'd want to risk everything to scratch even a torturous itch.  And finally: What if you started digging, wrecked your marriage and learned your daughter is "yours"? … If you're considering any action at all, have a lawyer vet it legally. Only then can you be confident whether truth-seeking serves your interests — and your family's — or smashes them to bits.

Is there any other common betrayal situation where neutral third parties would so strongly advise not looking to see if you've been betrayed?  I can't think of one.