All right then, I'd like you to give me an advice. I wasn't always open about sex, actually I never really discussed it too much. Then I met my wife, and after some time in our relationship, we have discovered she's got a pretty solid case of hypersexuality. No, not the teenage 'I'm a nyph, I love sex,' it's actually kind of bad. No psychological treatement helped, all it did was lessening the issue slightly. So now, we either have sex often enough - so often that I myself sometimes get horribly sick of it (guys, don't even TRY to make comments about how great that is, I get it often enough and it's not,) or she starts taking potentially dangerous and personality changing dampening pills. Or my wife gets horribly depressed and generally unhappy.
I think you weren't waiting for real answers, but:
I've seen one TV documentary on the same subject, and there they tried to "lessen" the sexual drive of the female with some kind of closeness/intimacy exercises by the couple. Ie. all kinds of cuddling was approved, but not sexual acts. That way the oversexual person kinda learned that fulfilling intimacy can be non-sexual too.
I'm not saying that necessarily always works, depends what is the real reason for hypersexuality. If it is related mostly to hormones, trying to make one "less sexual" is like trying to change a hormonally frigid person into a hypersexual one (without medication).
And yeah, I've also been in a situation (in another relationship) where I was the one wanting less sex, and it was not a nice situation to me, quite irritating actually. I guess it was one of the reasons we finally broke up.
Even currently, it is my gf who 95% of the time is the one making the initiative. So far it hasn't been a problem because 94% of the time I willingly comply. The good news is that I personally find my gf very sexy, so it doesn't take her that much effort to arouse me, unless I am very stressed out for some reason (e.g. work, or DRM).