Various masaail of Nikaah

Feeling jealous if husband takes a second wife

Q: Allah created both men and women differently such that a woman does not naturally feel to have more than one spouse at a time.

1. My question is that if it was in the nature of a male to have more than one wife as created by Allah then why are there naturally the feelings of jealousy or insecurities and intolerance that a woman feels about it? My mind and heart both know that Allahs plans are the best and I blindly trust in them but then why I feel annoyed and really bad about the fact of sharing my husband with someone else. I even feel annoyed when my husband teases me about angels of Jannat? Why has Allah put this feeling in us knowing the natural tendency of males? 

2. Though I know that there is nothing wrong in having more than one wife but I still feel uncomfortable and jealous about this fact. I would never be able to stand the fact of my husband marrying someone else. Does that mean that I am not a good believer as my husband constantly keeps saying that if I cannot tolerate the fact of my husband having another wife (suppose) then I am not a good muslimah. Is that so?

Mother telling the son to never remarry

Q: If a man got married and his mum told him that he must not marry again and he's been through hell in his marriage. His mum is late now amd his kids are grown up and working. He found somebody in his life who is going through as much as him. She was an orphan and now he wants to know if he can marry this woman despite what his late mum said. He is only living in the house because of his kids. Can you advise if he can marry and be happy again?