Truth is not only violated by falsehood; it may be equally outraged by silence.

A lie is not the only way to leave someone misinformed. Saying nothing when you know lets a false impression stand, and it does so without the risk of being contradicted. Silence feels innocent because it is passive, but the person left with the wrong picture is in the same position either way. Often the reason for it is not principle but a wish to avoid the conversation.

Notice the next moment you decide not to say something, and name the real reason. If it is kindness, or bad timing, let it rest. If it is avoidance, say the thing.