Main Idea of O. Henry's "The Gift of the Magi"

In the short story "The Gift of the Magi" by O. Henry, a young couple, Jim and Della, are deeply in love but financially struggling. As Christmas approaches, both desire to give each other a special gift. Della decides to sell her long, beautiful hair to buy a platinum chain for Jim's prized possession, his wristwatch. Meanwhile, Jim sells his watch to buy a set of combs for Della's hair. On Christmas Eve, their sacrifices reveal the depth of their love but also the irony of their situation, leading to a poignant understanding of selfless love.