A Midsummer Night's Epic Confusion

I just spent the morning helping my little sis with her homework - namely, summarising the narrative nightmare that is William Shakespeare's A Midsummer Night's Dream. The biggest issue is the love quadrangle between the four idiots - uh, I mean protagonists - of the play. Basically, in short: Lysander loves Hermia who is supposed to marry Demetrius who is adored by Helena whom Lysander gets potioned to love as does Demetrius then both girls freak out but Puck depotions Lysander and they all live happily ever after. Got that?

No? Okay, here's a diagram, borrowed from this very helpful page:

Ayup.

The astute reader may note that Demetrius is still potioned to love Helena at the end. In other words, he's been mind controlled to love someone against his will. I find it hard to think of this as a happy ending, frankly. What happens if the potion's effects have an expiry date? And even if they don't, can Helena be happy knowing (as she seems to suspect in one of the final scenes) that Demetrius' love isn't quite genuine? And what about poor mind-controlled Demetrius? In short, Oberon is a jerk.

Mind you, do we have the right to expect a genuine happy ending from the man who wrote Macbeth, Hamlet, Julius Caesar, Othello and all the rest? Didn't think so.