In Much Ado About Nothing, I believe Benedick and Beatrice have made themselves believe that they have hated each other, when really it was love all along. Each has taken on this spiteful persona regarding love as a form of denying their true feelings for each other. Through exaggerated language, Benedick plays the role of a macho bachelor and, in response, Beatrice plays the role of the unquiet maid. Both, really, are impostors until the end, when they admit their true love through words and actions.
Through some trickery from their friends, Benedick and Beatrice reveal their love two ways: privately and publicly. Benedick drops his macho persona to become a defender of women, as he openly challenges Claudio to a duel, at Beatrice's prompting. Beatrice, too, becomes a loving matriarch to Hero as she rests her reputation on Hero being slandered. Together, the two show their love for others, thereby weakening their defenses and revealing their love for each other. Love, after all, is sacrifice.
Later, Benedick and Beatrice's love is expressed inwardly through writing. Observe:
And I'll be sworn upon't that he loves her;
For here's a paper written in his hand,
A halting sonnet of his own pure brain,
Fashion'd to Beatrice.
And here's another
Writ in my cousin's hand, stolen from her pocket,
Containing her affection unto Benedick.
A miracle! here's our own hands against our hearts.
Come, I will have thee; but, by this light, I take
thee for pity.
I would not deny you; but, by this good day, I yield
upon great persuasion; and partly to save your life,
for I was told you were in a consumption.
Peace! I will stop your mouth.
Though their sarcasm continues, they kiss to confirm inwardly and outwardly that they currently love and have loved each other for some time.