Historically, women only meetings are a space
where women can organize politically and discuss about things that makes men uncomfortable. It also acts as a reprieve from men, who treated women as literal property. Typically these meetings would have a theme that most men do not have interest in: a tea party or a knitting group. Book clubs are a very good cover (IIRC, in some cases the meetings were
technically open to everyone but we're de facto women exclusive because the organizers knew that most men look down on women dominated hobbies and are too prideful to engage with them). This is because of society's negative view on the act of women just fucking talking with each other. Women's talk is belittled and scoffed at as frivolous or meaningless all throughout history; in fact the word
gossip, idle and rumourous chat, is derived from
godsibb, a close female friend of a mother right after her child's birth. Birth used to be an event only attended by women, and the godmother of the child would be the mothers close friend and someone she talked a lot with because what else is a woman going to do while resting after labor. It is theorized that
gossip gathered a negative connotation around the 15th century as women who's speech was a bit too troublesome would have their mouths sealed shut with an iron contraption called
the scold's bridle, also know as the gossip's bridle. In modern times, women's talk is more casual and is just like any other conversation among friends of any sex with the exception of the topics of dating, women's health, warnings about other men, emotional support, etc.
This isn't to discourage you from attending these clubs that are dominated by women, it's simply to provide some context as to why women typically do not trust men in gatherings where it is expected to be exclusively women and for me to sperg a bit about women's history as it's (surprise, surprise) not common knowledge. Please go to these events and enjoy them by all means.