Do you have any information on the study(ies) she’s talking about? Who did 'em, when, with what means? I ask because, anectotally, I’d love something to blame my low (read: nonexistent) libido on, and going off hormonal birth control correlates time-wise, and is as good as any other hypothesis I’ve heard…
But honestly, my only knowledge on the subject is that being ON hormonal birth control can kill the libido. I believe that’s somewhere in the side effects on that package insert the pharmacist kept giving me. I’ve never heard anything about that effect from going off of it.
Another thing to consider is whether she might be (unconsciously perhaps) nervous as hell about whatever form of birth control you’ve switched to, or the idea of baby-makin’ if that’s what you’ve decided on. Worriy, stress and ambivalence kill the female libido quicker than a … thing that kills libido quickly. (I need Sampiro’s gift with words here, and it ain’t coming this early in the morning!)
(FWIW, if the rest of your relationship is OK, I doubt she’s “borking” someone else. The female libido tends to, in my experience, increase the more it’s…uh…exercised. When I’m enjoying the company of another man (open marriage), I want my husband even more. Sort of a catch 22 - if I could increase my libido to sleep with someone - anyone - then my libido would increase. Sometimes Nature sucks.)