Interestingly, the title of Much Ado About Nothing plays into the theme of this comedy as the word nothing is often used by Shakespeare as a euphemism for the female sex organ; further, this word in Elizabethan times was pronounced "noting," thus providing a richer sense to the comedy as it if replete with "noting," or watching and listening in such as the famous scene of Benedick and Beatrice's overhearing conversations of much interest to them as well as the plan to have Claudio "witness" the infidelity of his betrothed.
In addition, there is "much to do about nothing" with wit. About the witty repartee between Beatrice and Benedick, the renowned critic Harold Bloom writes in his Shakespeare: The Invention of the Human,
With every exchange between the fencing lovers, the abyss glitters, and their mutual wit does not so much defend against other selves as it defends against meaninglessness. They make much ado about nothing because they know that nothing will come of nothing, and so they speak again.
When, for instance, Leonato speaks of his niece Beatrice, he remarks that there is "a skirmish of wit between them." To this, Beatrice wittingly comments upon Benedick,
Alas, he get nothing by that. In our last conflict four of his five wits went halting off, and now is the man governed by one....(1.1.43-44).
One of the great comic scenes of Shakespeare is the confrontation between the accomplished wit of Beatrice and Benedick, whom Beatrice begins to control with this superb wit [remember the earlier explanation of "nothing"]:
Bene. I do love nothing in the world so well as you--is not that strange?
Beat. As strange as the thing I know not. It were as possible for me to say I loved nothing so well as you, but believe me not; and yet I lie not; I confess nothing, nor I deny nothing. I am sorry for my cousin.
Bene. By my sword, Beatrice, thou lovest me....
Beat. Will you not eat your word?
Bene. With no sauce that can be devised to it. I protest I love thee.
Beat. Why then God forgive me.
Bene. What offence, sweet Beatrice?
Beat. You have stayed me in a happy hour, I was about to protest I loved you.
Bene. And do it with all thy heart.
Beat. I love you with so much of my heart that none is left to protest.
Bene. Come, bid me do anything for thee.
Beat. Kill Claudio! (4.1.266-288)
Much of the humor of the play also stems from the conniving plots of the characters: Don John, the Prince of Aragon's illegitimate brother, engages his follower Borachio in a malicious plot to lead Claudio to believe that he has witnessed Hero in a most compromising situation on the eve of her wedding, when in fact the couple are Hero's maid Margaret with Borachio. So, at the wedding ceremony, Claudio denounces Hero as unfaithful; she faints, and Leonato, on the suggestion of the Friar, pronounces her dead. It is at this time that Beatrice insistss that Benedick kill Claudio. But, the intervention of providence comes in the form of the bumbling, "malprop-prone" [he utters malaproprisms] Constable Dogberry, who overhears Borachio bragging of his exploit, intervenes and exposes the deceit.
With nothing to do with wit, there is also nothing to do about marriage. Certainly, the marriage of Benedick and Beatrice is no romantic bliss. But, it does not matter; for, Benedick and Beatrice, neither of whom with such wits as are theirs will be outraged or defeated, agree to take their chances with each other in this Shakespearean comedy.