Previously, Undine disliked looking in mirrors. Here, it seems that she dislikes Hubert because his extravagant financial habits force her to consider how she herself might look from the outside. Hubert also activates Undine’s competitive instincts, since he competes directly with her for a share of the family money. Humorously, marrying a rich heiress turns out to be expensive, because Hubert needs to pay off his debts to prove that he’s a worthwhile marriage candidate.