This isn't a "bad" book per se, but it's curiously pointless. While Blank sets out to limn the history of heterosexuality as a concept, what she really ends up doing at great length and to little new effect, is to write about the legal and social concepts of marriage (companionate and otherwise) and the cultural history of dating. None of this is fresh, none of this has not been done dozens of times before decades before, most more thoroughly and from a more deeply informed historical and/or philosophical perspective. None of this illuminates our current understanding of what's "heterosexual" and what's "homosexual". In fact, beyond the brief personal revelations that open and close the volume, there's virtually nothing here I haven't read many, many times over.
I guess I just can't imagine who's the audience for this book. Anyone seriously interested in the subject of sexuality, sexual/gender identity, and the history of how society and individuals assign labels is not going to find anything fresh, interesting, or particularly useful here. And those who aren't especially interested or knowledgeable are probably not going to read or seek out this book. Sooo?