1. Zeng Jiaqiao has been favored by his family since he was a child and has a strong dependence on his family. Once he meets When it comes to emotional problems, this dependence will be amplified.
2. Zeng Jiaqiao was a forensic doctor, but he missed the opportunity for promotion because he was afraid of blood, which may have given him an inferiority complex.
3. Zeng Jiaqiao and Jin Ben are people from two different worlds. Their relationship has problems and eventually leads to a breakup, which may make Zeng Jiaqiao feel lost and desperate.
4. Nie Baoyi may have made a negative evaluation of Zeng Jiaqiao's dependence and affection, which made Zeng Jiaqiao feel abandoned and betrayed, which may have caused him extreme anger and despair.
Please note that the above is just my speculation based on what I know. There may be other reasons why Zeng Jiaqiao killed Nie Baoyi.