First ever post on here just to say that I cannot get over a 23-year-old writing an advice book on anything, least of all sex and relationships.
I'm 26 and have actually dated and slept around quite a bit, and I still wouldn't DREAM of attempting to do anything like that. I know someone in her management or whatever probably just told her to write about this topic, but it comes off so arrogant to think you know anything worth sharing. I'd need someone to be at least in their late thirties to even consider reading their advice on this, and even that still feels quite young to be honest when you think about how much happens in the many years after that.
I almost feel a bit sorry for her because I definitely went through a period of time when I overcompensated when talking about sex because I wasn't very confident in myself and how I looked, but I also don't feel bad because I was 18/19 doing that and I also wasn't projecting that on to younger, more impressionable girls (because I assume the only people who would be interested in or feel like they got anything from this book would be 14-year-olds at the oldest).
EDIT: Also that story about sleeping with her friend reads exactly like how I would've written about the guy I swore I was fine just casually sleeping with when I was 18-19 but was actually completely infatuated with. She's really just put all her cards on the table there, it'd be a bit heartbreaking to read if it weren't entirely her decision to publish that.