Who proposes the idea of marriage between Romeo and Juliet?

Juliet proposes the idea of marriage to Romeo on the very night that they meet.  In Act 2, scene 2 (otherwise known as the balcony scene), Juliet becomes so obsessed over the idea that she must be sure that Romeo is truly in love with her that she tells him that if he really loves her and wants to be with her, then he must marry her when she says,

     "Three words, dear Romeo, and good night indeed.
      If that thy bent of love be honourable,
      Thy purpose marriage, send me word to-morrow, 
      By one that I'll procure to come to thee,
      Where and what time thou wilt perform the rite;"  (A. 2, s. 2, lines 148-152)

On the following day, Romeo does, in fact , give the Nurse information about when the marriage will take place.