The prevailing mood at the end of Act 3, Scene 1 is one of foreboding.  The future does not look bright for either of the men involved in the bond plot--Shylock and Antonio.  Shylock's daughter Jessica has run off with Lorenzo and with Shylock's jewels, and Shylock's friend Tubal tells Shylock of Jessica's spending spree across Europe at her father's expense.   Tubal is able to cheer up Shylock with the news that "Antonio is certainly undone" because his ships have sunk and he cannot pay his creditors.

In contrast, Scene 2 of Act 3 is lyrical and happy. The characters speak in verse instead of the businesslike prose of Scene 1's Venetian setting.  Bassanio chooses the correct casket, and Portia cheerfully accepts his proposal, all while surrounded by music.  Thus, while the bond plot unravels in Scene 1, the casket plot ends happily.