I see an emerging crisis among teenagers in the UK (and probably the western world as a whole) which I believe arises (at least partly) because we make them socially useless, and 'trap' them in childhood and in school, at precisely the time of their lives when they have most energy...
The result is unhappy, frustrated, angry teenagers - and (as one experienced practitioner once described it to me) "boys act out and girls act in". This is a tendency not a universal rule, of course; but we do see more boys involved in anti-social behaviour and the criminal justice system, and more girls self-harming and developing eating disorders.
I must admit that I do not see a 'sudden and universal deterioration in girls' mental health, starting in primary school and devastating the teen years'. I think this is an ongoing pattern, which could be clearly seen in my own school days (30+ years ago). Social pressures are different then, and there was less focus on 'perfect' body image and more on being a 'good girl'. There has always been, and still is, pressure on girls to conform to expectations, rather than to be themselves.
Yet girls have always been 'allowed' to have mental health problems: when it comes to teenage distress, it seems to me that our society wants to view girls as 'sad', and boys as 'bad'.
One of your central themes in Raising Boys was that boys need fathers. Boys struggle, you argued, when their fathers are not actively and positively involved in their upbringing. I agreed with this, and have seen it happen with my own DS1 and countless other boys. It certainly seems to me that men have withdrawn from raising boys and girls in our society - not totally (of course there are some wonderful, very involved dads), but to a very large extent.
On the other hand, mothers have very definitely not withdrawn from raising their children. We hang on in there, through thick and thin, as these boards show.
So my question is this - if there is a crisis for girls now - is this also due to men's withdrawal from parenting? What do you think fathers offer girls that mothers cannot? Or do you have some other explanation...?