Q: Help! I've just spotted my manager's profile on an online dating site. He's married with two kids and I know his wife. I feel sick about it. What should I do?
Jeremy says: There's no perfect answer. Tell his wife - and you've interfered massively in the lives of two other people; and with unknowable, potentially disastrous consequences.
Tell your manager that you've identified him online - and you immediately become part of his deceit. It would do nothing to help his wife and would probably have no limiting effect on his behaviour.
The most likely outcome would simply to make him more circumspect. And you're left knowing what you know and somehow trying to be natural whenever you see his wife. It's a horror.
It feels craven - but in the absence of any better option, you should pretend to yourself that you never spotted your manager's profile and do absolutely nothing. There's just a chance that his fling will be a temporary one, that it goes undetected and that his marriage will survive and prosper.
He might not deserve it, but that would be a good outcome. Any other action you take would make even that slim chance less likely.
And if it does all come out, and their marriage falls apart, you must never admit to his wife that you knew. She'll never understand why you felt you couldn't tell her.
Jeremy Bullmore is a former creative director and chairman of J Walter Thompson London. Email him your problems at firstname.lastname@example.org. Regrettably, no correspondence can be entered into.