Why is dreaming the only possible answer for what happens to the characters throughout the play "A Midsummer Night's Dream?"
- Falling in love with someone you rejected long before.
- Falling out of love with someone you risked your life for.
- Some guy whose head turns into that of an ass.
- A (married) woman falling for said ass.
It's like the cliche: "You can't write this stuff." This play is all about the willful suspension of disbelief, and a great show to understand and perform. Everything comes together so perfectly, that only magic could cause such chaos and resolve it so easily.
And who wouldn't want a little bit of magic? Helena loved Demetrius, and he loved her at one time-- why not get him to love her again? This also clears the way for Hermia and Lysander to marry, because her father preferred Demetrius while he continued his pursuit of Hermia. This also makes Theseus look more attractive to Hippolyta because he gets to be the "good guy" and allow his subjects to follow their hearts. And a "full-of-himself" actor got his come-uppance and a lovely little fantasy to remember.
It's all a bit too much. So maybe we're the ones dreaming. We can come up with some crazy stuff, and sometimes we're better for the experience.