How does Aeneas know that his wife has died?

Aeneas learns of his wife Creusa's death during his escape from Troy when he realizes she is missing as they flee the city. In his search for her, he encounters her spirit, who reveals that she has been taken by fate and urges him to continue his journey to found a new city. This encounter confirms to Aeneas that she has died, and he is left with a sense of loss and duty to fulfill his destiny.