Crossword puzzle clue "pen friends who write letters to each other"

Pen ___ (friends who write letters to each other)

Besties who also literally hate each other's guts but we're besties but we hate each other so much it hurts sometimes

"To write is to write is to write . . ." writer

Like each answer in this puzzle - also each word in each clue - in length

Friends who don't keep secrets from each other?

Kind of commercial pact where two countries agree to treat each other as well as any other

Theme answer count, amount of letters in each, word hidden in each, and, when repeated twice, today's date

The other other other woman