On Sierra Shaw's 25th birthday, her boyfriend, Benson Gray, puts an engagement ring on another woman's finger. He tells Sierra to be more magnanimous and transforms her birthday party into a party for the woman in his arms.Fine, then. He can go to her, too.Sierra demands a breakup, but Benson is unfazed. He makes a bet with his friends—he says Sierra will come groveling at his feet in less than three days…However, the next time he sees her, her arm is in his uncle's. She throws a marriage certificate in his face and says, "I'm your aunt now, nephew dearest. Don't forget to address me properly!"