Why is Penelope upset at the song of the bard?

Penelope is upset at the song of the bard because it reminds her of her husband Odysseus and his long absence from home. The bard's tales of heroic deeds and battles stir her feelings of longing and sorrow, highlighting her loneliness and uncertainty about Odysseus's fate. The song brings back painful memories, making her acutely aware of her plight as a faithful wife waiting for a husband who may never return.