OOO I like this answer ty anon!! Raven and Rosefinch were NOT created together actually, the contrasting/complementing nature of their designs and personalities was mere coincidence despite how they look!

Rosefinch was created years ago, and Raven was created around 1.5 year ago (as a Docsona), but it was later that we decided to make them interact and even later that they develop proper feelings for each other.