The irony of marriage
Marriage is an institution where two people in love unite to become one bond. Therefore, the foundation of marriage is love. When Frank falls in love with Mary, he decides to marry her. Ironically, Frank's parents are against his decision to marry Mary because she comes from a low-income family. Frank's parents believe he should marry a rich woman whether he loves her or not.
The irony of Mr. Rodgers
Mary is an illegitimate child. According to Dr. Thorne, Mary was born out of wedlock, and he decided to keep that secret for a long to maintain the girl's reputation. Ironically, Dr. Thorne later reveals that Mary is the daughter of Mr. Rodgers, a wealthy person who spends his money on alcohol and other luxurious activities. The paradox is that Mr. Rodgers does not care about his daughter and has no elaborate plan to ensure she gets part of his inheritance.
Dramatic irony
Readers have a hint that Frank is likely to rebel against her parents when he falls in love with Mary. Frank's parents are sure he will follow the orders to marry a rich wife to get his family out of debt. However, Frank's parents are disappointed when they learn that he has decided to disobey them to marry a poor woman.
