How were obstacles between Beatrice and Benedick overcome and true love preserved in Shakespeare's Much Ado About Nothing ?

In this play of Shakespeare it is not so much how true
love conquers obstacles but Shakespeare's major theme of appearances vs. Reality and
social expectations, in his tragedy's such as Macbeth we see how deception can have
devastating results, but in this comedy, he simply alludes to the potential tragedy that
lies in the antics of those who, apart from Don John, have good
intentions.

But in answer to your question, love brings
together characters, Beatrice and Benedick, character's who themselves have said they
will never marry. They are both strong characters, witty and independent, love creates a
situation in which they no longer have to be alone. Their love also shows some deep
realisations for both characters about the ideals they have so far lived under. Both are
quite unaware of how sharp their wit is and the adverse effects it can have on those to
whom it is directed. But together they seem to moderate each other a bit and become more
aware of what they say. Their love has shown a development of their characters.
Shakespeare alludes to the fact they had a relationship in the past which was ended due
to Benedicks antics, and clearly Beatrice has not forgiven him, while Benedick obviously
does not see it as his problem. Both hide behind their quick wit, showing beneath the
surface they are both very sensitive. Beatrice is actually a very venerable character as
is Benedick, and when their love develops they embrace it as this venerability can no
longer be seen as a weakness but an endearing trait. So essentially love brings out a
truth in their characters, an acceptance of their lives and the fact happinness can
actually be found from love and it is not weak to admit
it.

For Hero and Claudio (Claudio being a much weaker
character in comparison) their love perhaps cannot be considered as true love. Claudio
asks Leonnato if Hero is his only heir, alluding to his potential desire for significant
economic gain from a marriage. And when Margaret is mistaken for Hero, Claudio does not
seek an explanation or confrontation with Hero immediately, instead choosing to publicly
humiliate her. He is ruled by his quick to fire feelings as opposed to the rationality
someone like Beatrice has which allows her to give Hero the benefit of doubt. Claudio
perhaps is more interested in the idea of love as opposed to love itself of which he is
rather naive. Hero is simply a delightful young woman, polite, generous and loyal. Her
innocence is her most endearing quality, one which Claudio very nearly destroys, but
their love does succeed in the end, showing true love promotes
forgiveness.