These are real life events

1,A man have been diagnosed with Cancer.His wife of umpteen years leave him alone,lodge a case against him and his parents for money and custody of his children.The man barely can walk by his own.He is forced to come to the court.

Note : The couple were a very happy couple and this happened in India,a very conservative country which values relationships and divorce is a taboo is India.People would see divorcees as shit in India.

A man wouldn't even do this to his enemy.I know these two guys who were the biggest enemies and one guy was diagnosed with tumor and the other guy gave him financial support,emotional support.

2,A man and woman enjoys their life in college,going to bike rides and shit and because of some reasons,the professor lodges a case against the guy using her name (like the guy abused her or something).At first,the woman supports the guy but then slowly retreats and support the professor forgetting every good moments she and her best friend had.

Note:The girl is from an utter poor family.The guy literally gave her a fucking life.

What makes a woman hate the person who loved them the most and they loved the most and do really hurtful things that a man wouldn't even think about doing to even his own enemy.Are there any scientific reasons?