Why is it scary to tell our secrets to people closest to us?

Have you ever noticed that sometimes it’s easier to tell a stranger something scary about yourself than your best friend?

I’ve run into this multiple times. Sometimes, I eventually get around to telling those closest to me too, but sometimes I never do. Sometimes, I never get past telling strangers.

Why is that? What makes it somehow okay to tell strangers? Perhaps more importantly, what makes it somehow not okay to tell those closest to us?