How does Paris explain his haste in arranging the marriage, as seen in Act 4, Scene 1?
In his conversation with the friar, Paris requests that his wedding date to Juliet be moved up. The friar, who has recently married Romeo and Juliet, is understandably concerned about this turn of events and questions Paris about it.
Paris responds that it is Lord Capulet's idea to move up the wedding, which gels with the earlier scene that we read between Juliet and Capulet. Paris goes on to say that Juliet is deeply upset over the death of Tybalt and that Capulet is hopeful, both that the wedding will prove a welcome distraction, and that Paris can be in a better position to console her as a husband, rather than just a mere suitor.
In reality, Juliet is not crying over Tybalt at all, but rather over the banishment of her husband, Romeo, and the tragic events that surrounded it. It is the shortened time frame of the wedding that will force Juliet's hand to take action, and will ultimately lead to the play's tragic end.