Through Puck's trickery and his ability to assume any of their voices, the four lovers all end up back where they started and fall asleep without seeing each other. Puck drops the love potion onto Lysander's eyes, saying that "when thou wak'st thou tak'st / True delight in the sight / of they former lover's eye" (3.3.39-41) and that all shall then be well.
Puck uses his magic to fulfill Oberon's plan to ensure a balanced love between the four lovers. When they wake up, what was a tragedy will be a comedy. And sos as the lovers sleeps their lives have been rewritten by the fairies one more time.