You should pay back your friends.
Sarah receives extra money that she wasn't expecting, and she knows that she should pay back Rachel for a recent loan.
Sarah needs to decide what to do with her extra money.
Sarah pays Rachel back for the loan and thanks her for being a good friend.
Sarah purchases a new stereo system with her extra money, and has a dance party at her house.
Rachel values Sarah's friendship and her feelings of trust and intimacy are strengthened.
When Rachel realizes what Sarah has done, she is hurt and feels resentful toward Sarah's decision.