In O. Henry's short story "The Gift of the Magi," do you think Della and Jim made such sacrifices because they were not confident of their love for each other?
No, Jim and Della were more than confident in how much they loved each other. There is no evidence in the story that they were insecure or uncertain about what they felt. They loved one another so much that each was prepared to sacrifice his and her most precious possession as an expression of their love. Their love for each other transcended physical boundaries and therefore they could sacrifice for one another out of love. It is not that they felt making a gift of their most treasured possessions would win their partners over and make them more affectionate or loving, no. Their sacrifices were not about themselves, but about the other. Their generosity was selfless and they expected no reward.
The story makes it quite clear that Della and Jim were truly in love. The depth of their feelings for each other went beyond their physical circumstances. Although they were desperately poor, their love provide them with the sustenance they needed. The purity of their love is emphasised by their willingness to let go of their most precious material possessions.
If these two had not had such depth in feeling for each other, it would have been eminently noticeable. They would most probably have been presented as argumentative and unhappy, constantly bickering about the lack of money, resources and privileges. Della would have resented Jim for earning so little and he would have felt the same of her for being such a burden. But these sentiments are not explored at all, for Della and Jim's existence is idyllic and their love makes it so.
It is not the value of the gifts nor the fact that they had made these unselfish sacrifices for each other which is important. The importance lies in the depth of their love as illustrated by the following lines:
Eight dollars a week or a million a year--what is the difference? A mathematician or a wit would give you the wrong answer.
The difference is that without true love nothing has value, for real love is priceless and nothing, but nothing, can compare to it.