Let us first examine the relationship between Romeo and his parents and what their actions reveal. We learn, at the beginning of the play, that both Lord and Lady Montague share a deep concern for the welfare of their son. At the end of the brawl between the two feuding families, lady Montague desperately enquires about her son's whereabouts. She asks Benvolio:
O, where is Romeo? saw you him to-day?
Right glad I am he was not at this fray.
Lord Montague makes it clear that he has been observing his son, taking note of his actions. Truly the acts of a caring father. He mentions how Romeo had been keeping to himself, closing his curtains and staying in his room, how he has seen him in tears. He expresses concern for his son's apparent depression, stating:
Black and portentous must this humour prove,
Unless good counsel may the cause remove.
Lord Montague admits that he does not know the reason for Romeo's grievous state and says that he has been shunned by his son, who has refused to talk to him about what he feels.
... to himself so secret and so close,
So far from sounding and discovery,
Romeo is obviously sulking and does not wish to confide in anyone, least of all his parents - typical teenage behaviour! It is clear, however, that his parents are worried and are more than prepared to help. Lord Montague mentions:
Could we but learn from whence his sorrows grow.
We would as willingly give cure as know.
When Romeo appears at the scene, Lord Montague urges Benvolio to find the true reason for Romeo's melancholy:
I would thou wert so happy by thy stay,
To hear true shrift.
There is very little interaction between Romeo and his parents throughout the play, but we do learn in Act 5 that they were deeply distraught by Romeo's banishment, so much so that Lady Montague died on hearing the devastating news. Lord Montague declares:
Alas, my liege, my wife is dead to-night;
Grief of my son's exile hath stopp'd her breath:
Lord Montague is utterly overwhelmed by his son's death and on seeing Romeo's lifeless body wails:
O thou untaught! what manners is in this?
To press before thy father to a grave?
The play places greater emphasis on the relationship between Juliet and her parents and there is much more focus on their interaction. It quickly becomes apparent that Juliet's parents want what is best for her, but wish to press her to abide to their decisions and their choices, such as for example, in choosing a husband. Lady Capulet asks Juliet in Act 1, scene 3:
How stands your disposition to be married?
Juliet expresses her unwillingness to even think about it, but her mother insists that she should consider wedlock now since the county Paris has shown his interest in her. She instructs Juliet to look at Paris and consider him an apt groom. Juliet reluctantly agrees.
Juliet rebels against her parents' choice of life partner after she falls in love with Romeo, to such an extent that she secretly weds him. After Romeo had killed Tybalt, Juliet openly lies to her mother, expressing hate for Romeo for committing such a foul deed. Her mother's declaration about 'joyful tidings' related to Juliet's marriage to Paris is venomously rejected by Juliet who declares:
I will not marry yet; and, when I do, I swear,
It shall be Romeo, whom you know I hate,
Rather than Paris.
Ironic words indeed. Juliet is confronted by her father and when he hears of her resistance he is greatly upset. He commands that Juliet go to church on Thursday to be wed. He refuses to listen to Juliet's pleas and warns her:
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. Wife, we scarce thought us blest
That God had lent us but this only child;
But now I see this one is one too much,
And that we have a curse in having her:
Harsh words indeed. It is clear that the relationship between Juliet and her parents has broken down irrevocably. Even though Lady Capulet tries to intervene, it is to no avail. Lord Capulet threatens to disown Juliet if she does not do as he commands and her mother, subservient to her husband, is forced, at this point, to also reject her daughter. It is this dramatic altercation which eventually forces Juliet's hand and leads to the tragic series of events culminating in her, Romeo and Paris' deaths.
It is clear, however, that both Lord and Lady Capulet love their daughter, for they enquire after her well-being. Lady Capulet still seeks some kind of appeasement from Juliet when she later offers to assist her - a request which is disdainfully rejected by Juliet. Further emphasis of their love is provided at the moment they discover Juliet's lifeless body and are both completely engulfed by grief.