"Love can be destructive." True. Using Romeo and Juliet is a good choice for supporting evidence.
The easiest way to support that statement is to use the fact that had Romeo and Juliet not fallen in love with each other, they would both still be alive. Romeo thinks Juliet is dead, so he kills himself. Juliet wakes up, sees Romeo is dead, and she kills herself. The whole thing wouldn't have happened, if they had never met. In other words, their love for each other destroyed any chance for a long life.
Juliet's love for Romeo also destroyed her relationship with her mother and father. In Act 3, Scene 5, Juliet tells her parents that she will not marry Paris. She will marry Romeo.
I will not marry yet; and, when I do, I swear,
It shall be Romeo, whom you know I hate,
Rather than Paris.
Her news doesn't go over very well. Especially with Lord Capulet.
Hang thee, young baggage! disobedient wretch!
I tell thee what: get thee to church o' Thursday,
Or never after look me in the face:
Speak not, reply not, do not answer me;
My fingers itch.
From that point forward, Juliet's relationship with her parents is tarnished for the rest of her life (which isn't that much longer anyway). Once again, her love for Romeo is more of a destructive force than a uniting force.