Why do nerissa and gratiano have an argument?

Answer 1

Nerissa and Gratiano have an argument because Gratiano took off his ring which Portia gave to him on their wedding day which was the same day as Portia and Bassanio's, and Nerissa made Gratiano swear or made him vow that he would never take the ring off until the hour of his death.

"You swore to me when I did give it to you.

That you should wear it till your hour of death,

And that it should lie with you in your grave."

Act 5, Scene one, line 152 - 154.