Answer:
I would invite Della over Dinner.
Step-by-step explanation:
Della and Jim are newlywed partners in O. Henry's short story "The Gift of The Magi". They both decided to give each other a precious gift on the occasion of Christmas. Because of poor financial condition, they both sell their most precious possessions - Della her lustrous long hair and Jim his gold pocket watch inherited from his father.
It would be a tough choice because both characters are each other's replica. They are identical. Both sacrifice their most precious possessions just to make the other happy.
It would also be tough decision to invite only one of them, because without the other partner, the invited one would not be the person he or she really is.
The preference of Della over Jim for inviting over dinner seems only because of the fact that she is presented and described more in the story. I know her a bit more than I know Jim.