Queen Victoria visited France, and Eugenie visited England..

.. quite often and became very close.  One can imagine being a Queen or Empress made it difficult to talk openly and honestly with anyone other than another royal.

We know they traded fashion secrets, because history and the museums document that after a Eugenie visit to England, Victoria would sport the latest Parisian Worth design that Eugenie had just worn on her visit.

(Painting: The Formal introduction of Queen Victoria of England in 1855 to Empress Eugenie of France.   They were actually good friends already, having met informally at Eugenie’s estate)