Entering into a relationship with someone projects the idea that you are willing to reveal your truest self, your worst weaknesses, your most playful part and basically everything about you.
It is presupposed that you are willing to trust them with your secrets and that they’d be willing to do the same.
You see, the thing about trust is that it grows. No one expects you to lay yourself bare before someone before the relationship reaches anywhere significant, but the willingness to do so has to always be present.
If you are thinking of entering into a relationship with someone and you are seeing signs that they can’t be trusted with secrets, it is better to not even enter into a relationship with them at all.