How does Juliet go about telling Paris that she does not love him without lying to him?

It would have been easy for her to tell him that she did not love him without lying, since she did not love him. She could have said "I don't love you and I don't want to marry you." Her problem is that if she says that, her father has said that he will disown her completely. Since she does not know how to get along in the world on her own (never having left the house except to go to church), she takes him at his Word and does not want that to happen. So she has to pretend that she loves Paris and is going along with the marriage without lying which is trickier.

Paris: Happily met, my lady and my wife!

Juliet: That may be, sir, when I may be a wife. (thinks: I'm not your wife yet, and I don't plan to be ever)

Paris: What may be must be, love, on Thursday next.

Juliet: What must be shall be. (thinks: yeah, whatever happens will happen. But it won't be me marrying you, bud.)

Paris: Come you to make confession to this father?

Juliet: To answer that, I should confess to you. (thinks: it's none of your business why I want to talk to the Friar)

Paris: Do not deny to him that you love me.

Juliet: I will confess to you that I love him (thinks: and the less we talk about me loving you the better)

Paris: So will ye, I am sure, that you love me.

Juliet: (thinks: oh, let it alone!) If I do so, it will be of more price, being spoke behind your back, than to your face. (thinks: I won't say it behind your back or anywhere)

Paris: Poor soul, thy face is much abused by tears.

Juliet: The tears have got small victory by that, for it was bad enough before their spite. (thinks: I'm ugly, man! Find yourself another girl.)

. . .

Paris: Thy face is mine and thou hast sland'red it.

Juliet: It may be so, for it is not mine own. (thinks: because I'm giving you a line of double-talk. Don't you get it, cloth-head?)