Yes, actually after Keira returned from the demon world, Ludwig has his memories back already. He became extra sensitive ( his power) since his soul is mixing with the demon. He sent letters to Keira to come home,so Keira change location where she stayed. She came back and defeated Cossette in this battle. Ragibach was imprisoned in the demon world. Keira went to magic tower even if Zeke was against it. She went there to tell Erez that she won their bet. Ludwig got his memories back even before the bet expired iirc. He told her what she wants and she told him that she wants him to void the contract between him and her father. Erez teased Keira of being a good daughter and she tell Erez that she forgive her father. That's it,she went home. And no romance at all.
Guys just tell me one thing does the father recover his memories? I want him to feel extra miserable