Lord Capulet is obviously embarrassed and conflicted by Paris's request to marry Juliet. On the one hand, Capulet could not ask for a more perfect suitor for his daughter's hand. Paris is rich and belongs to a very important family. Not only that, but the young man is a kinsman to Escalus, the prince of Verona. Paris, in effect, is making him an offer he can't refuse. On the other hand, Capulet is still attached to his daughter. He is not ready to give her up. She is still his darling, his little girl. He knows that if she marries she will soon be having a baby--and this could be a dangerous event in any woman's life, but especially in that of a young girl. When Paris brings up the issue by asking:
But now, my lord, what say you to my suit?
it shows that Juliet's father has been stalling. He is afraid to say no but doesn't want to say yes. He apparently did not give Paris a straight answer before because he was hoping the young man might lose interest, or fall for another girl. Capulet continues to stall.
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.
Capulet is in the awkward position of having a daughter who, though only thirteen, is so ravishingly lovely that young men are attracted to her like bees to a succulent flower. Proof of this is to be seen in the fact that the girl will very soon have two of the most eligible young men in Verona, Paris and Romeo, competing for her love. Shakespeare may have made Juliet so young to enhance the idea of her exceptional beauty. When a girl is especially attractive in every respect, her father will have a hard time keeping her under his wing.
Younger than she are happy mothers made.
And Capulet voices one of his major objections.
And too soon marr'd are those so early made.
This is what everybody thinks about the question of whether Juliet is too young to be married. Marriage leads to pregnancy, and a thirteen- or fourteen-year-old girl could die in childbirth, or have a miscarriage, or be forced to undergo a very crude, painful, and dangerous caesarean delivery. We all know that Juliet is too young.
Capulet continues to stall. If it were any other young man than Paris, Juliet's father might just say no. But Paris is too important a person and too attractive a suitor. Capulet encourages him to woo his daughter and try to be patient. He also invites Paris to his ball and suggests that the young man meet the most beautiful girls in Verona and compare them with his daughter. These balls are usually given for the specific purpose of bringing debutantes and eligible bachelors together. Capulet thinks that Paris will find some other girl if he is not genuinely in love with Juliet, or else he will be all the more attracted to Juliet and willing to wait a little longer to have her as his bride.
Among fresh female buds shall you this night
Inherit at my house. Hear all, all see,
And like her most whose merit most shall be;
Which, amongst view of many, mine, being one,
May stand in number, though in reck'ning none.
This is the situation when Romeo crashes the party and makes everything infinitely more complicated.