I'd Rather Eat Chocolate is the story of a woman and her husband sucessfully negotiating a large difference in sex drive. It's wonkers that this hasn't been done before, because it very intelligently addresses that one big surprise people who choose not to have sex before marriage face. It's funny and concise, and manages to give usefully detailed descriptions without getting gross or exhibitionist. I'd Rather Eat Chocolate covers a lot that inexperienced engaged couples would be wise to discuss.
I hate that she attributes the gap in libido solely to biological gender. For someone so articulate about the gendered sexual pressure she's under, she's impressively immune to the possibility that patriarchy could have adversely influenced her sexuality. By making it all about gender she also re-enforces the stigmatization of women who are extremely interested in sex, and especially men who aren't. This story and others like it are needed for all the low libido individuals out there (and those who might wish to partner them), not just the women.
But I love Sewell's description of coming to terms with her sexuality in a context where female sexuality is framed in terms of male desire. It's awesome to read how healthy it was for her to resist cultural pressure and refuse to have sex she didn't want, despite the complications; that's a lesson for everyone, regardless of how often they prefer to have sex.