rensley's decision to flee the castle is obviously something he has thought about for a long time, and him thinking it's the best decision is valid. BUT the misunderstandings with the duke and his wishes for betrothal with another duchess is something that can be straighten with just one talk.
nevertheless, the fantastical aspect of the series really amazes me. and with another revelation that duke shapeshifts into something other than human was a cherry on top. I'm so excited how their relationship will continue after the duke's romantic confession :)