Why does Calypso hold Odysseus prisoner on her island?

Calypso holds Odysseus prisoner on her island, Ogygia, because she is deeply in love with him and wants to make him her immortal husband. She offers him a life of comfort and eternal youth, hoping to keep him by her side. Despite her affection, Odysseus longs to return to Ithaca and reunite with his wife, Penelope, which creates a conflict between his desires and Calypso's. Ultimately, the gods intervene, leading to Odysseus's release.