[Dog Gone]

What business is it for his boss to be enquiring about extramarital affairs in the first place?

[cosine]

For obvious reasons, you don't want someone with the power to prosecute to have a history that makes him subject to being bribed, bludgeoned, or blackmailed. In many respects, prosecutors have more power to wreck individual lives than the President. Having an extramarital affair is a bad thing. Lying about it is worse.

Employers have to trust employees in order to get work done. In many jobs, people fill out an extensive employment form when hired. It asks lots of questions. You affirm that you have answered honestly. If you lie and the employer later finds out, you can be fired, no questions asked.