Shakespeare tells us a great deal about relationships in Much Ado About Nothing. He particularly shows us what character traits are necessary for people to possess in order for relationships to be successful, such as trust, forgiveness, and lack of pride.
The importance of trust is especially portrayed through Claudio and Hero's relationship. Twice Claudio allowed himself to be tricked into believing that someone he loved had questionable character by a person that he already knew had questionable character. The first time he was tricked, the morally questionable Don John led Claudio to believe that Claudio's dear friend Don Pedro had deceived him and is courting Hero for himself instead of keeping his promise and courting her for Claudio's sake. We see Claudio being gullible enough to be duped in this manner when we see him proclaim:
'Tis certain so; the prince wooes for himself.
Friendship is constant in all other things
Save in the office and affairs of love. (II.i.152-154)
Had Claudio persevered in trusting his friend whom he loved, he never would have allowed himself to be duped by Don John. Of course, Claudio allows himself to be duped a second time as well, this time allowing himself to believe that Hero has been unfaithful. Again, had he allowed himself to trust his instinctual beliefs about Hero's modesty and virtue and to question Don John's character, he never would have allowed himself to be duped this second time, showing us just how important trust is in relationships.
We see Shakespeare show us how important forgiveness is in relationships when we see Hero forgive Claudio for his atrocious behavior. Instead, she allows herself to be born anew through forgiveness and proceed with the wedding. We see Hero proclaim her rebirth in her lines:
And when I lived I was your other wife; ...
And when you loved you were my other husband.
One Hero died defiled; but I do live,
And surely as I live, I am a maid. (V.iv.61-66)
Hero's ability to forgive and be reborn anew shows us just how vital forgiveness is in maintaining relationships.
The importance of lack of pride is exhibited through both Beatrice and Benedick. Both are criticized for being too prideful and led to believe that the one will not proclaim his/her love for the other because the other is too proud to reciprocate. However, we see Benedick denounce his pride in the lines:
I did never think to marry. I must not seem proud. Happy are they that hear their detractions and can put them to mending.(II.iii.207-209)
Likewise, we see Beatrice denounce her own pride when she proclaims:
Contempt, farewell! and maiden pride, adieu!
No glory lives behind the back of such.
And, Benedick, love on; I will requite thee. (III.i.111-113)
Hence, since both Bendick and Beatrice decide to denounce their pride in order to be united, we see from this that lack of pride is an essential character trait in a relationship.
I believe Shakespeare demonstrates that all relationships are different. Shakespeare does this by contrasting Hero and Claudio's relationship, to Benedick and Beatrice's.
Hero is a quiet, obedient, shy and feminine woman who marries the valiant, manly and noble Claudio. Claudio acts as if he has purchased Hero, and she is his asset. This relationship was one view of the role of gender; a patriarchal family with a dominating male and an obedient female.
However, the relationship with Benedick and Beatrice is much more different. Beatrice is an outspoken, intelligent, witty and confident woman who possesses masculine characterisitcs, like a need for revenge. She enjoys exchanging insults with Benedick.
I agree with tamarakh, as well. Shakespeare also shows that different personalities work better with different people. Could you imagine Claudio and Beatrice being together? It just wouldn't work, and same for the idea of Hero and Benedick being married. Different characteristics attract different people.