During Aeyron's dream of King's Landing in the future he sees Joanna, it goes like this:' Aeyron hugged her tighter not wanting to let her go but he felt her slowly evaporate.
Joanna got up and walked towards the door,
“Don’t go” Aeyron begged but Joanna gave him a smile and disappeared forever…'
-There's foreshadowing here, Aeyron attempts to keep Joanna but she evaporates out of his touch, foreshadowing that Aeyron will not marry Joanna in the end.
-The premature meeting between Aeyron and Joanna and their abrupt departure also symbolises when Aeyron finally gets to Joanna she dies-'disappearing forever'