Secret

I was watching one of Kangxi episode and it got me thinking about this topic.
Secret.
Everybody has secrets, be it those that can be known or not.
So how do couples then say "wo men zhi jian bu hui you mi mi?"
And eventually realize that the other half is hiding some secrets when they found out something that they did not know of initially.
and there comes the mistrust and what not.
Is that really then called we have no secrets between us?
I thought... secrets are not meant to be said?


Everybody has secrets, isn't it?