Prove that the suffering in Romeo and Juliet is the responsibitlity of the parents.I am looking for irresponsible acts they committed, actions they...

It is interesting that you want to isolate Romeo and
Juliet's parents, since there are two other grown-ups in the play that have much more
actual effect on the choices that Romeo and Juliet make -- The Friar and the
Nurse.

Lord and Lady Montague show their lack of
involvement in the opening scene of the play, when they confess to Benvolio that they
have no idea why their son is so melancholy and ask him to find out; and Lord and Lady
Capulet have no idea what is going on right under their noses throughout the course of
the play between their daughter and Romeo.

So, it is hard
to hold Lords and Ladies Montague and Capulet accountable for the suffering of
Romeo and Juliet, since this is a Tragedy and, as such, the
suffering stems from the choices made by the two main
characters.

Romeo and Juliet choose to keep their love
secret.  They choose to marry.  Juliet chooses to take the poison and pretend to be
dead.  Romeo chooses to fly to Juliet's side when he learns that she is "dead" and kill
himself.  And Juliet chooses to kill herself when she awakes and find Romeo dead beside
her.  All of these choices are made because both Romeo and Juliet suffer from the same
tragic flaw -- They are over-hasty in their actions.

All
the above being said, there are definitely things that the parents do (and don't do)
which contribute to the reasons that Romeo and Juliet choose as they do.  The most
glaring is that both families do nothing to end the feud.  Much of the choosing of
secrecy can be attributed to the ongoing feud, which the parents refuse to end until it
is too late, both Romeo and Juliet are dead.

Lord Capulet
is also guilty of motivating Juliet's choices when he insists that she marry Paris,
when, originally he had protested both that she was too young to marry, and that he
would defer to her in whether she was willing to wed.  His actions in Act IV really push
the haste with which Juliet decides to follow the Friar's desperate plan and contribute
to the final suffering by motivating Juliet's action.

But,
even though the parents are responsible for prolonging the feud and Lord Capulet pushes
Juliet by decreeing that she wed or "starve in the streets," the suffering of the play
is still the responsibility of the two main characters and the result of the choices
they make out of haste.

For more on the the roles of choice
and haste in this Tragedy, please follow the links below.