In Shakespeare's Romeo and Juliet, Capulet's suddenly changes his mind concerning marriage—why does he do this?
In Shakespeare's Romeo and Juliet, when Paris first approaches Capulet regarding a marriage proposal for Juliet, her father is hesitant to make a firm commitment. He believes Juliet is too young (giving the sense that perhaps he is not ready to let her leave home so soon, and wants her to be in agreement).
But saying o'er what I have said before:
My child is yet a stranger in the world,
She hath not seen the change of fourteen years;
Let two more summers wither in their pride
Ere we may think her ripe to be a bride. (I.ii.7-11)
This is very different than the father who demands that she marry Paris immediately, or be thrown out onto the street, which for a woman of that time would have been almost a death sentence. (For Juliet, the only real option for a young woman of her station would be to join a convent or starve on the streets.)
...What is this?
‘Proud’—and ‘I thank you’—and ‘I thank you not’—
And yet ‘not proud’? Mistress minion you,
Thank me no thankings, nor proud me no prouds,
But fettle your fine joints 'gainst Thursday next
To go with Paris to Saint Peter's Church,
Or I will drag thee on a hurdle thither. (III.iv.152-158)
I don't know if there is a clear answer as to why Capulet seems to so radically and cruelly change his mind. However, as a parent, I can only imagine that it may have something to do with Tybalt's death. We don't get a sense of Capulet being overly fond of Tybalt. During the masquerade, when Romeo and Juliet meet, Capulet is more than reasonable about Romeo's attendance than Tybalt.
Content thee, gentle coz, let him alone.
He bears him like a portly gentleman,
And, to say truth, Verona brags of him(70)
To be a virtuous and well-govern'd youth.
I would not for the wealth of all this town
Here in my house do him disparagement. (I.v.68-74)
However, perhaps Capulet sees Tybalt's death as a harbinger of what could happen to Juliet, as Romeo avenges Mercutio's death—not for suspicion of Romeo, but concern in that long life of the young has now becomes more uncertain, and death closer to home.
Alive in triumph, and Mercutio slain?
Away to heaven respective lenity,
And fire-ey'd fury be my conduct now!(125)
Now, Tybalt, take the ‘villain’ back again
That late thou gavest me; for Mercutio's soul
Is but a little way above our heads,
Staying for thine to keep him company.
Either thou or I, or both, must go with him. (130)
Thou, wretched boy, that didst consort him here,
Shalt with him hence.
This shall determine that.
They fight. Tybalt falls. (III.i.123-132)
For all that Tybalt is a trouble-maker, perhaps we can assume that Capulet worries for the safety of his daughter, hoping to have her settled should anything more drastic occur in his life.
There is also the need for Juliet to be forced to take drastic action to avoid the wedding. Romeo and Juliet have been presented as star-crossed lovers, whose fate has long been decided, regardless of what they do (in the eyes of the author and his Elizabethan audience).
Capulet's anguish at the loss of his daughter is real, so I believe we can assume he was frustrated with recent events and had no time for Juliet's resistance—he wanted her safe, not knowing she had already married:
O heavens! O wife, look how our daughter bleeds! This dagger hath mista'en, for, lo, his house Is empty on the back of Montague, And it missheathed in my daughter's bosom! (V.iii.213-216)