I have a 13 year old son who seems to have the weight of the world on his shoulders.
If there is trouble in school, it's the boys who are blamed automatically. Not sure what the solution is to this, dd is 14 and when there's trouble or something serious happens they investigate and don't blame anybody.
He wanted to join a computer coding lunch time club, he can't as it's girls only.
Nothing wrong with a female only coding club, can your son speak to a teacher about maybe him starting a male coding club? Or could you phone the school about arranging someone for the boys? Or look into after school coding type groups. Dd is one of a very small number of girls who have chosen computer sciences as part of her options, the school asked her and another girl if they'd help organise a club for the younger girls in the hope it'll encourage them choose it as part of their options. They have the only club during a lunch break twice a week but there's mixed sex alternatives and the boys are told they are free to organise a male only one if they wish but it's not happened yet, every now and then a parent will complain on Facebook about it not being fair but at their same time their son isn't bothered enough to give up his own time to organise and run a male club.
He has been taught to hold doors open for girls, ladies before gentlemen etc.-
Who is teaching him this though? You and his father can counteract this and tell him girls can open doors themselves but he should the door open for people who need help, men and women. If a boy is struggling to open a door with his hands full he should help, or if a boy or girls is going through right behind him then it's polite to keep it open but most girls are capable of opening it herself and he doesn't need to rush up and open it for her.
He thinks when he grows up and gets married he will have to earn enough to support his wife and kids on his own as it's always the Mum who's a stay at home parent.
Again, you and his father can teach him that it's not always the Mum at all. Teach him to be a hands on Dad, to take an equal share in the housework and looking after his children. You could discuss why it's often the woman giving up her job to stay at home, things like woman being paid more, or how housework and cleaning and looking after children is often seen as women's work and society not placing value in it so a lot of men don't choose it. If he doesn't want the traditional patriarchial family set up he doesn't have to.
He gets upset at school when he feels unfairly treated but he can't show it because "boys don't get upset".
In what ways does he feel schools been unfairly treated him? Assuming he freely expresses his emotions and discusses feelings with you and his Dad if they are being unfair with him can you speak to them yourself? Does he have an adult at school he likes and can talk to if it's pupils being unfair to him?
Kids pick up a lot views and expectiaons from those closest to him, if he thinks it's always the woman who stays at home is the because all the women he knows quit work? Does he see men in his family doing their share in their home? Did his Dad do a fair share of housework and childcare when they were growing up?
If you don't know any family or friends where the Mam doesn't work then point out families in the media where this isn't the case.
He doesn't need the world on his young shoulders, he should be worrying about getting good grades and having fun instead of his adult married life that he doesn't have to have if he doesn't want it.