Compare the relationship between Juliet and her parents from Act III, Scene 5 to Act IV scene 5.

In Act III, Scene 5 Juliet's parents inform her that they have promised her hand in marriage to Count Paris. Capulet has changed his mind about Paris (earlier he had required the Count to "win" Juliet's love before consenting) and believes the family needs a "day of joy" after the death of Tybalt. Juliet's parents know nothing about Romeo and it is ironic that they would break the news to their daughter just after she...

In Act III, Scene 5 Juliet's parents inform her that they have promised her hand in marriage to Count Paris. Capulet has changed his mind about Paris (earlier he had required the Count to "win" Juliet's love before consenting) and believes the family needs a "day of joy" after the death of Tybalt. Juliet's parents know nothing about Romeo and it is ironic that they would break the news to their daughter just after she has been with Romeo on the couple's honeymoon night.

When Juliet refuses to marry Paris (because she is already married to Romeo), Lord Capulet becomes enraged and Lady Capulet treats her coldly. Capulet threatens to disown her and put her out in the street. He says,

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.

While not quite as demonstrative as her husband, Lady Capulet is also angry  at Juliet and refuses to be of any assistance when Juliet asks for some reprieve. Lady Capulet says,

Talk not to me, for I’ll not speak a word.
Do as thou wilt, for I have done with thee.

Juliet eventually seeks advice from Friar Lawrence who devises the plan for her to fake her death and avoid the marriage with Paris. When she returns home she basically lies to her father and tells him she will do whatever he wants. She says in Act IV, Scene 2,

By holy Lawrence to fall prostrate here [Kneeling.]
To beg your pardon. Pardon, I beseech you.
Henceforward I am ever ruled by you.

Juliet also treats her mother cordially in Scene 3 just before she takes the potion which will render her lifeless for almost two days. When she is discovered supposedly dead, her parents are distraught and mournfully praise their daughter. Lady Capulet says in Scene 5,

O me! O me! My child, my only life,
Revive, look up, or I will die with thee.
Help, help! Call help.

And Lord Capulet is heartbroken at finding Juliet. He echoes his wife's words, 

Despised, distressèd, hated, martyred, killed!
Uncomfortable time, why cam’st thou now
To murder, murder our solemnity?
O child! O child! My soul and not my child!
Dead art thou! Alack, my child is dead,
And with my child my joys are burièd.

In retrospect, the relationship doesn't really change. Juliet is lying to her parents throughout these scenes. She never reveals her relationship with Romeo, even when presented with the marriage to Paris. In Act IV, Scene 5 she is also deceiving them by faking her death. Honesty is totally lacking in the relationship from the very moment Juliet meets Romeo.