Question: how to know if she in a rebound relationship?
Answer: Signal One: He's Using Her to Forget You. ... 
Signal Two: Your Ex Decided to Date Someone Who Is the Total Opposite of You. ... 
Signal Three: Suddenly You Can Give Her What She Wants. ... 
Signal Four: Zero Percent Success Rate. ... 
Signal Five: If He Is Making Common Attraction and Relationship Blunders. ... 
Signal Six: Suddenly, He's Insecure.