For the most part, Twelfth Night is a look at society's foolish behavior. The title Twelfth Night alone refers to foolish behavior in that it refers to the holiday known as the Feast of Epiphany. The Feast of Epiphany is held on the twelfth day after Christmas and celebrates the arrival of the Three Wise men who came bearing their gifts to baby Jesus. While one would expect the Feast of Epiphany to be similar to other Christmas celebrations, apparently in Elizabethan times it was a time of "bawdy" behavior, as well as a "time of masques, revels, defiance of authority, and general foolishness" ("Shakespeare's Twelfth Night"). One of the common foolish social behaviors Shakespeare points out in the play surrounds the feelings of love or sexuality. In fact, one literary critic found in Shakespeare For Students argues that love in Twelfth Night is really just a further act of disguise that parallels all of the other acts of disguise in the play (eNotes, Twelfth Night Esssay: "Worm i'the bud: The Games of Love in Twelfth Night"). Hence, one thing we can make of the hasty manner in which characters in the play fall in love and get married is that their activities are, for the most part, simply representing the acts of foolish behavior that is such a dominant theme in the play.
Looking at Duke Orsino, we can see clearly just how much love in the play is being used as an act of disguise. Duke Orsino's love for Olivia is not really genuine love; it's more of an obsession. Shakespeare For Students even argues that he is really "in love with love," or the idea of being in love ("Worm i'the bud"). As a result, his fantasy of loving Olivia is really merely an excuse to be self-adsorbed. Hence, his proclaimed feelings of love are really just self-love and self-absorption in disguise. We can especially see his self-absorption in his opening scene. Shakespeare For Students points out that the "words 'I,' 'me,' and 'mine' occur ten times" within the opening scene. We can especially see his self-absorption in the passage:
O, when mine eyes did see Olivia first,
Methought she purg'd the air of pestilence!
That instant was I turn'd into a hart[deer];
And my desires, like fell and cruel hounds,
E'er since pursue me. (I.i.19-24)
While this passage appears to be a proclamation of his love for Olivia, Olivia is really not the main subject matter, but rather his feelings and his thoughts, showing us just how self-absorbed he truly is. Likewise, when he first knowingly falls in love with Viola, his exclamation is, "I shall have share in this most happy wreck" (V.i.276). Again, even here his focus is on himself and the self-satisfaction that love would bring him. Hence, even with Viola, the idea of love is merely a way to disguise the feelings of longing for self-satisfaction, or sexual desire. What is more, the things the characters do to gain sexual satisfaction, true to life, are foolish behaviors. As Shakespeare For Students also finally asserts, Twelfth Night explores the reasons behind man's foolish behavior with respect to society and declares that the most dominant motive for foolish behavior is the "most basic and defining activity of human kind: sex" ("Worm i'the bud").