If you’ve ever felt that someone in your life has been keeping a secret from you, you can use today’s idiom, to “keep someone in the dark”. It is used when we want to talk about a person who doesn’t tell another person about something; in other words they are keeping information from the other person. For example:
I think there’s a problem with my wife’s health, but she hasn’t said anything about it. I hate it when she keeps me in the dark like that!
There are rumors of my company merging with another one, but my boss is keeping us in the dark about it.
I know there’s something wrong! Please tell me what it is! Don’t keep me in the dark like this!
We’ve kept the children in the dark for too long about our plan to get a divorce. I think it’s time we told them.
This expression can be used in personal or business situations because it is neither formal nor casual in tone.