William Shakespeare's play "A Midsummer Night's Dream" has four different pairs of lovers. In the case of each pair, there is some conflict which interferes with the course of true love, although in all four cases we do get a happy ending.
1. Hermia and Lysander: Hermia and Lysander love each other but Hermia's father wants her to marry Demetrius. Puck anoints Lysander's eyes by mistake, so he falls in love with Helena, but then corrects his mistake.
2. Helena and Demetrius: Hermia loves Demetrius. In the past Demetrius loved her, but he has since fallen in love with Hermia. Puck anoints Demetrius' eyes to make him love Helena again.
3. Oberon and Titania: Oberon and Titania are married but quarreling over a changeling, and Oberon causes Titania to fall temporarily in love with Bottom as part of a plot to regain the changeling.
Thus an overall commentary on the love plots in the play could be Lysander's line in Act I Scene 1:
The course of true love never did run smooth.
4. Theseus and Hippolyta: Hippolyta was the Queen of the Amazons and was conquered by Theseus and compelled to marry him.