Unrequited love

All of them do to varying degrees. Viola loves Orsino but he loves Olivia. Olivia, however, loves Viola (disguised as Cicero).

Much ado about nothing. Beatrice and Benedict pretend they don't like each other for much of the play even though they do. Claudio falls out of love with Hero.

Midsummer- By accident Helena comes across Lysander, who was previously in love with Hermia, and wakes him up. He immediately falls in love with her and starts to chase her through the woods. Now Hermia will be upset about loosing her love. Together they arrive where Oberon is watching, and he realizes the mistake. Oberon then puts the pansy juice onto Demetrius's eyelids, who upon waking up also falls in love with Helena.