Aeneas ends his story, but Dido is already burning with love. After the feast she cannot sleep, and in the morning she confides in her sister, praising Aeneas. If she had not irrevocably decided not to remarry after the murder of her husband, she says, she might be tempted, since now for the first time she feels love again. But she says she could never allow herself to yield to that love. Anna persuades her that it is absurd to condemn herself to a lonely life like that, especially since her kingdom is surrounded by enemies, and she needs the help of a man like Aeneas. Together they can create a glorious Punic (Phoenician) kingdom. So Dido gives way to her passion and puts all her attention on Aeneas, leaving the building of the city neglected. Juno sees what Venus and Cupid have done and at first is angry, but then suggests that Venus and she should forget their quarrel and bring Dido and Aeneas together, uniting the two peoples under Aeneas. Venus pretends to agree, only expressing a doubt that such a union is what Jupiter wants. Juno says she'll handle Jupiter. But first, when the Trojans and Tyrians are out hunting, she will bring on the marriage. So she creates a rainstorm, and sees to it that Aeneas and Dido seek refuge in the same cave, where they come together in what Juno, and Dido, call marriage.
Rumor, the powerful god that can spread evil stories with such speed, spreads the story of the affair between Dido and Aeneas, and the king of the surrounding area, who had hoped to marry Dido himself, prays indignantly to Jupiter. Jupiter hears and orders Mercury to go to Aeneas and bring the god's commands. His mother didn't save him from the Greeks for this, but to become in Italy the father of a race that will give laws to the whole earth. If he doesn't care about such glory for himself, he must not deny it to his son. He must sail!
Mercury finds Aeneas happily participating in building the new city of Carthage, dressed in a cloak given him by Dido, and reproaches him with being the servant of a woman, forgetting his destiny. He delivers Jupiter's message, and Aeneas is stunned and immediately wants to obey and flee Carthage, but what can he say to Dido? He orders his men to get the ships ready, while he looks for the right time to say the right words to Dido. But Dido hears that the ships are being made ready before he can speak, and she flies into a helpless rage, accusing and reproaching him. By their marriage, by all she has done for him she begs him to at least put off his voyage till summer. If only she had conceived a son, she says, she would not feel so completely deserted, defeated. Aeneas with painful effort maintains complete self-control. He owes her so much, he says, but he never did marry her. If he could have had his life as he wanted it, he would be rebuilding Troy. But now he has been told by the gods that Italy is to be his homeland, and she must not prevent him from going there. Every night in his dreams Anchises warns him, and now Mercury himself has ordered him to go. He must obey his fate.
Dido is enraged yet more by his apparent lack of pity for her. She tells him to go, but threatens to haunt him with her revenge. She leaves, and he has to let all he would like to say to her go unsaid. Loving her, he longs to ease her sorrow, but pius Aeneas must go to his fleet, where all work doubly hard to get the ships to sea once he comes.
Dido is almost crazy with grief, but not yet ready to give up. She sends Anna to plead with him to postpone his going just long enough for her to learn to bear the pain. Anna pleads, but Aeneas resists her pleas and his own feelings as a mighty oak tree resists a storm. Then Dido wants only to die.
She pretends to her sister that she is going to work a magic spell to bring Aeneas back or set her free from her love. She creates a funeral pyre and puts an effigy of Aeneas on it, along with his sword. Aeneas is asleep on his ship, but a dream warns him to leave immediately. Seeing the ships gone in the morning, Dido cries out in rage and despair, wishing she had destroyed them all. In a moment of more calm she thinks of all the accomplishments of her life, and how happy it would have been if the Trojans had never come. Her last prayer is that Aeneas may face horrible warfare in Italy and die before his time, and that her countrymen may war against his descendants. She sends her companion away on a pretext, mounts the pyre she has built, and stabs herself with Aeneas's sword. Too late her sister rushes back, only to hold Dido as she dies, set free at last from her death struggle by the gods in an act of mercy, allowed because her death was not merited or fated but the result of being taken over by frenzy.
We would have expected to hear of Aeneas's falling in love, after seeing fully how weak and vulnerable he is when he lands on the shores of Africa, but Virgil keeps all the focus on Dido. Perhaps he hesitated to show a Roman hero in the making as entrapped by passion; in any case, he uses all the power of his art to make us feel how completely Dido is taken over by the fire of love, and then by rage and despair when her love is betrayed. Few people have read Book 4 without weeping for Dido, and many have had so much sympathy for her that they feel no sympathy at all for Aeneas, who betrays what she believes at least is his commitment to her, all because of the gods and his destiny and his duty to his son and father. Surely Virgil is really condemning the whole idea of sacrificing human happiness in the name of destiny? Others have argued that such a reaction ignores Virgil's real (and very Roman) purpose of showing how dangerous passion is, and how important it is to be able to withstand it. If Aeneas is to become a true Roman hero, he must withstand Dido's pleas. He must obey Jupiter's commands, and he must put duty first.
But he still has a long way to go, or he would never have allowed himself to enter the relationship with her in the first place, nor would it have taken a messenger from Jupiter to beat him into leaving. Perhaps most persuasive again is the interpretation that does justice to both sides: Yes, Aeneas had to leave, and Dido's giving way to passion is not only pathetic but at the end almost horrible; at the same time, Virgil is making us feel deeply both the tragedy of Dido and the sadness of Aeneas's having once again to give up the ordinary human joy of loving and being loved in order to pursue a destiny that has no real meaning for him.