隐情

我看他说话吞吞吐吐的，这件事背后一定有什么隐情。

From the way he hesitated while speaking, there must be something he is hiding about the matter.

既然她不想说，说明有自己的隐情，我们就别再问了。

Since she doesn't want to talk about it, she must have her own private reasons, so we should stop asking.