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.

Monday! ha, ha! Well, Wednesday is too soon,
O' Thursday let it be: o' Thursday, tell her,
She shall be married to this noble earl.
Will you be ready? do you like this haste? (Act 3, Scene 4)

When Lady Capulet asks Juliet about Paris, she gives what can only be described as an evasive answer.

I'll look to like, if looking liking move:
But no more deep will I endart mine eye
Than your consent gives strength to make it fly. (Act 1, Scene 3)

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.