What is ironic about Capulet saying that "Wednesday is too soon" for Paris and Juliet to get married in Romeo and Juliet?
It is ironic that Capulet says Wednesday is too soon because he is pushing for a fast wedding.
Capulet wants Juliet to get married. As far as he is concerned, she is of age and ripe for a politically expedient marriage. Capulet only pushes the wedding back one day. What difference does it make to Juliet? He knows she does not want to get married.
When Lady Capulet asks Juliet about Paris, she gives what can only be described as an evasive answer.
Juliet is in a bind. She has no interest in her father’s match. Then she marries Romeo in secret. Her family has no idea that she is already married, so her father pushes her to marry Paris. The marriage is what’s best for him, so it is what’s best for her. Juliet is supposed to do what her father says, no matter what.
The reality is that Juliet’s forced marriage to Paris caused her to fake her death, which led to both Romeo and Juliet ending up dead. This is all part of the problem. No one communicates, and everyone is sneaky. Juliet’s father is not empathetic and believes that she should obey him no matter what. Juliet is hardly the obedient daughter. The family feud, ridiculous as it is, makes this worse because she really can’t tell him about Romeo.
Capulet’s stubbornness and Juliet’s sneakiness ends in three deaths (Romeo also kills Paris). After they realize what happens, the Montagues and Capulets bury their feud. Again, ironically, it took the deaths of their children to give their families a future.
To fully understand the answer to this question, you have to understand what is meant by "irony."
There are three types of irony. Verbal irony is similar to sarcasm. It takes place when the speaker/writer says something different, often the opposite, of what they mean. Situational irony is when the outcome of a situation is different than what is expected. Dramatic irony is when the audience knows something that the characters do not.
Capulet's statement is an example of situational irony. Capulet has already said that he didn't want Juliet to marry until she was a couple of years older, and he also said that he wanted Paris to woo Juliet and let her decide if she wanted to marry him. When Juliet refuses to marry Paris, her father becomes furious, but then Tybalt is slain and Romeo banished. Juliet becomes very distraught and her parents think it is because of her cousin Tybalt's death. Therefore, Capulet's decision to move the wedding up to Wednesday is different than what we would expect. We think he is a stern but loving father who cares about his daughter's well-being and happiness. When he starts discussing the wedding in light of Juliet's sorrow over the death of her cousin, we would expect him to say something like, "Let's wait until this tragedy is behind us and Juliet feels better before marrying her off to Paris." We're surprised that he instead moves the wedding up one day, and also that he seems so jovial with Paris. Does Capulet not feel any sorrow about his nephew's death, or how it has affected his only child? That's situational irony -- the outcome is different than what we would expect.