In the play "The Importance of Being Earnest" explain the theme of marriage.
You might benefit from widening your discussion of marriage in this excellent and hilarious play to also referring to the way that Wilde treats sentimentalism and romantic love. Wilde clearly mocks such extreme approaches to romance in this play by having Gwendolen and Cecily love a man only because of the name that he has rather than anything else. Note what Gwendolen tells Jack at the beginning of the play:
...my ideal has always been to love someone of the name of Ernest. There is something in that name that inspires absolute confidence. The moment Algernon first mentioned to me that she had a friend calle Ernest, I knew I was destined to love you.
Both Gwendolen and Cecily, therefore, only love based on the name of their beloved rather than other factors such as beauty, wealth and social standing. Of course Cecily takes this even further, by having "created" an entire relationship between her and Algernon even before meeting him. Thus it is that Cecily declares to Algernon, when he declares his love to her, that they have already been engaged for three months:
Worn out by your entire ignorance of my existence, I determined to end the matter one way or the other, and after a long struggle with myself I accepted you under this dear old tree here.
Thus, in this hilarious play, the theme of excessive romantic love is parodied throughout by the two principal female characters, Gwendolen and Cecily, who love only on the basis of the name of their beloved rather than anything else.