The Show Must Go On
For a romantic comedy, the ending to Shakespeare in Love is pretty tragic. But before we get to the tragic denouement, first the dramatic climax.
Throughout the film, Viola has masqueraded as a man to play Romeo. But she's been exposed and expelled from the stage. However, just as the curtain is rising, the man playing Juliet can no longer play her. His voice as changed. So Viola returns taking on the very role she inspired. She is reversing the gender-reversal by playing her own gender. It's so simple, it's complicated.
The audience gasps, either because a woman is one stage, or they can't possibly believe a man could be that beautiful. And because Viola is a woman, she can play Juliet in a way that no man can. She plays opposite Shakespeare, as Romeo, and their love is so true, it burns up the stage. (Not literally. Put away the extinguisher.)
Shockingly, the Queen is there, and she settles a wager earlier "as to whether a play can show the very truth and nature of love." Her verdict: It can. We think the reason it does is because the two actors are in love. No other performance of this play, no matter how good it is, could ever be as passionate, unless the two leads were in a tragic romance of their own.
That Ship Has Sailed
Which brings us to the tragedy. As the Queen says, this is how it ends: "As stories must when love is denied: with tears, and a journey."
We get tears and a journey when Viola must leave with Lord Wessex, her husband, to America. Before she leaves, she inspires Will to write Twelfth Night in which he imagines her ship wrecks, killing everyone (especially Wessex who he probably fantasizes being eaten by sharks as well), but Viola survives. A comedy about a cross-dressing shipwreck survivor? (That sounds like a good sequel… or an episode of Gilligan's Island.)
Will almost quits writing, he's so depressed, but Viola tells him, "If my hurt is to be that you will write no more, then I shall be the sorrier." This puts her firmly in place not as a great actress or a passionate lover, but as Shakespeare's muse. It isn't the loss of her acting career or her freedom that she laments, but the possibly that this man might never write again.
Will finds hope in tragedy, which is easy enough for him considering he isn't being shipped across the Atlantic with a man he doesn't love. He immortalizes Viola as the heroine of Twelfth Night, saying "she will be my heroine for all time." Or at least until he needs to write another play.