I attended a talk she did last year off the back of
How We Love, the premise being "to reflect on her work past, present and future" in conversation with a host but she mainly bitched about men and talked about the research she'd been doing for
I Don't. It sounded heavily weighed toward being anti long term heteronormative relationships rather than marriage specifically, but I too will have to read the book to be sure

Her main point seemed to be, why would you engage with it at all if you knew the history? Regardless of your circumstances, if you choose to marry now you're endorsing what it stood for before. (Which I fundamentally disagree with FYI but hey ho.)
The blurb also mentions covering "the physical and social cost that comes with motherhood" so it'll be interesting to see how much she delves into that (harking back to earlier comments noting she doesn't speak out against motherhood, being a mother herself). I don't think that "cost" is marriage's fault by the way; rather capitalism and the way society is structured now. Which I guess you could argue is men's fault, as current society structure was basically established by the patriarchy...... But again, I'll have to read the book