Complex sentence: Rebound relationships are believed to be short-lived due to one partner's emotional instability and desire to distract themselves from a painful break up, and those emerging from serious relationships are often advised to avoid serious dating until their tumultuous emotions have calmed.
Split into simpler sentences: Rebound relationships are believed to be short-lived due to one partner's emotional instability and desire to distract themselves from a painful break up. Those emerging from serious relationships are often advised to avoid serious dating until their tumultuous emotions have calmed.