TS: It is ironic that Jim buys the combs for Della because Della cut her hair off and sold it to buy a watch fob.
CD: Jim had to sell his precious watch to buy Della the combs she has been wanting.
CM: Della thought she needed to buy Jim an expensive to make him happy.
CM: Jim felt like he needed to sell his watch to buy Della a really good gift.
CS: In conclusion, they thought by selling their precious gifts they could make the other feel happy, but they ended up not using the gifts till later.