In Shakespeare's Much Ado About Nothing, why is Claudio and Hero's love conventional?
The term "conventional" pertains to something...
...conforming or adhering to accepted standards, as of conduct or taste
In referring to "conventional love," perhaps one would need to acknowledge its antithesis, which is "affected" or pretended love. Because of the theme of appearance vs. reality in Shakespeare's Much Ado About Nothing, and the pretended (at least at first) love of Benedick and Beatrice, as opposed to the genuine love of Claudio and Hero, "conventional" may also come to mean (in this context) "genuine" love.
It could be said that Claudio and Hero's love is conventional (literally) because they become enamored as others do: they meet and fall in love. Perhaps it is conventional also because Hero shows the proper regard hoped for by Messinian society: devotion and faithfulness toward her soon-to-be husband. (Therefore, this love would be considered conventional.) Even after Hero is falsely accused of infidelity, she has not changed at all: she is still by nature the same dedicated, devoted and loving woman she was before Claudio completely loses his intelligence and faith in Hero by listening to lies perpetuated by Don John and Borachio.
Hero's love is conventional in the sense that it is genuine. She loves only Claudio. And based upon society's hopeful expectations of how a woman should act, being honorable and faithful, she would never bring shame upon Claudio by her actions. However, the doubt—the expectation of betrayal—is introduced by Benedick:
Because I will not do them the wrong to
mistrust any, I will do myself the right to trust none; and
the fine is, for the which I may go the finer, I will live a
Benedick notes that so as not to offend one woman by not trusting her, he will not trust any, and will never (he believes at this point) marry—ever. Benedick's suspicions reflect the worries of he and his peers about their lack of trust in the faithfulness of their women—in the play.
If Benedick does, indeed, represent what men of his time and culture anticipate they will face in loving a woman, then Hero is even more conventional, doing what is ideal and unlike what other women may be doing—exhibiting behavior desired and approved by Messinian society.
It is unfortunate that Claudio almost loses Hero before realizes how wonderful and dedicated she truly is. But Hero's love for him, and his realization of her goodness saves their relationship. Claudio believes that Hero is dead, and is ready to marry another without knowing her identity (she is veiled) and without love in his heart for her; but Hero surprises Claudio at the altar—she is the "veiled" bride:
And when I lived I was your other wife; [Unmasks.]
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)
In the end, Claudio (rewarded beyond perhaps what he deserves) marries a woman who is conventional because of all the goodness she possesses. And perhaps Claudio, based upon that time period, is conventional in being suspicious of his betrothed—it may be, however, that he is somewhat unconventional in leaving his fears and suspicions behind, to love Hero with a full heart.