What happens in Act 4 Scene 2 of A Midsummer Night’s Dream?

Act IV, scene ii makes a basic transition from sadness to joy as Bottom’s return transforms his fellow craftsmen’s sorrow and confusion into delight and eagerness. It is no coincidence that Bottom’s reappearance occurs almost simultaneously with the audience being told that the lovers have been married.

Who does Demetrius love at the end of Act 4?

Helena

They discover the four lovers asleep and wake them. Lysander now loves Hermia again, and Demetrius loves Helena.