In my opinion, throughout Act IV and V, the Capulets corporately experience the gamut of emotions. Since their daughter is now appearing to be cooperating with them at the beginning of the fourth Act, they are pleased.
Why, I am glad on't; this is well: stand up:
This is as't should be. Let me see the county;
Ay, marry, go, I say, and fetch him hither.
Now, afore God! this reverend holy friar,
Our whole city is much bound to him.
Capulet is so pleased that he agrees to arrange the wedding and act as the "housewife" for the event. He plans to see to it that everything gets done. This gesture demonstrates either control or genuine kindness to his wife, or maybe both.
Lady Capulet turns very helpful to Juliet as demonstrated in this quote:
What, are you busy, ho? need you my help?
Then when Juliet fakes her death, they both seem sincerely grieved as they mourn her death. Lady Capulet says:
Accursed, unhappy, wretched, hateful day!
Most miserable hour that e'er time saw
In lasting labour of his pilgrimage!
But one, poor one, one poor and loving child,
But one thing to rejoice and solace in,
And cruel death hath catch'd it from my sight!
Capulet responds similarly:
Despised, distressed, hated, martyr'd, kill'd!
Uncomfortable time, why camest 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 buried.
Although their mourning may be sincere, this also shows great selfishness on both their parts. They speak of Juliet as an object that death has taken and they consider how it affects each of them, not why she died.
The only other time we see them in Act V positions both of them to feel great remorse for what has happened... again.