That's exactly it, he thinks the mage used her to get over her so why can't he. -.- it's probably why he can't move in he is expecting to use people and is not even trying to let go of his feelings thinking Penelope is a magical pill to get over his love, I hope his ass falls in love with Penelope at the end before realizing he was an ass and Penelope obviously will reject him

I think the duke just wants to get over betty and seeing the mage got over her as he falls in love with Penelop, the duke think it's ok to use Penelope to get over betty TvT in others... He wants a rebound ☹