That Guide survey is being reported in the Guardian as well:
UK survey finds sharp decline in happiness of young women and girls
www.theguardian.com/lifeandstyle/2018/sep/19/uk-survey-finds-sharp-decline-in-happiness-of-young-women-and-girls
Unsurprisingly, no-one has yet connected this with the 4000% rise in girls wanting to be boys. 
It occurs to me that so much of this is just driven by pure, unadulterated capitalism. "Woman" has been colonised by marketing from meaning adult human female to meaning a collection of tropes that you can fulfil by shopping - make up, hair, clothes, sexual display.
These tropes are then used to justify objectification. To be a successful girl, you have to fulfil the tropes, but then you also justify being treated like a piece of meat. It's a Catch-22.
So the solution is - more capitalism! Just buy your way out of femaleness with hormones, surgery and - oh yes - a boi makeover.
This happens to boys as well, only failure as "Trope Man" means you get to be a non-man and buy their tropes instead.
At no point does anyone forgive their bodies for not being perfect Instagram-filtered marketing dreams. At no point do they realise they having a personality outside marketed stereotypes is normal.
Self acceptance just isn't profitable.