diary friend

A friend that that makes you feel like you could genuinely tell them ANYTHING without any judgment, someone who you have never worried about them spilling your secrets ever. Telling this friend something is like telling your diary, you can share any thought and it won’t be shared somewhere else.

Example 1:
Person A: Hey girl can I tell you something??
Person B: Of course, we’re diary friends!!

Example 2:
I wish my diary friend was here, I need to tell someone this

Diary friend

The diary friend is that one friend who you really trust with all of your secrets because you know they won't tell anyone. Often times the diary friend is used as a vent for trauma or personal problems such as mental health or relationships with other people.

You mean she trusts you with all her problems? You must be her Diary friend.