What is the dramatic significance of lines 28-55 in act 3, scene 1 in the development of the play?

In these lines the king, Claudius, tells his plan to his wife, the queen and Hamlet's mother, Gertrude. He and Polonius plan to hide and send Ophelia out to "bump into" Hamlet so that they can observe the interaction between them. Polonius thinks Hamlet's love for Ophelia, love that Polonius made her reject, is the cause of his madness, and Claudius wants to test this theory. Gertrude tells Ophelia that she hopes it is his love for Ophelia that has made him act so crazily, and she expresses her desire that Ophelia's "virtues / Will bring him to his wonted way again" (3.1.41-42). Polonius then instructs Ophelia to read from a book of prayer and look natural.  
One way in which this scene is dramatically significant is that Polonius has forced Ophelia to break off her relationship with Hamlet, an event that seems to have had a major effect on Hamlet's conception of women as well as his ability to trust others. Polonius told her that Hamlet would not be free to love her. However, we now learn that Gertrude would be happy if the two were to end up together. Therefore, Ophelia and Hamlet could have continued to be together, and he might not have gone so far off the deep end—going on to alienate Ophelia further, publicly humiliate her at the play, and tell her he never loved her. She might not, then, lose her wits later on in the play either. This is sadly ironic.