Simple answer, she's not attracted to you

I second R.C., it has nothing to do with seducing your GF, just coping with the boredom that comes up naturally in a couple. There's plenty of literature out there on that. Reminds me of the seven factors of sexual desire cited by some sex therapist (I think there are much more, but that's a good starter): novelty, risk, being forced to be apart, exploration, leisure time and absence of adult responsibilities. From what you're telling us, you got close to none of these in your couple.
Discuss about it with your GF, tell her what's your problem, and suggest solutions you find in the literature to solve it. I can't give you THE solution, I guess it's different for everybody. I heard a couple for whom starting spanking rekindled their desire. Find your own thing.

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We do what we have to do in order to do what we want to do.

In the end, your desires are likely both diminishing, as I suggested. You have to reestablish a different connection. When you focus so much on the other person as a partner and not as a sexual being, you begin to treat them that way. Then it becomes a conditioned response and their self-identity becomes more like what you have perceived her to be. The same for you. If you don't feel sexual, and she then doesn't see you as sexual, there is no anticipation or sexual attraction and then the sexual interaction feels forced rather than like it came naturally. This is probably why she is "planning" sex, so that you can be in the mood and ready to ignite her passion. Your dynamic isn't aiding to your sexual appetite, and sometimes being too good of "friends" per say can cause you two to overlook this aspect of your relationship. It's common. This is often why things become stale, and you have to remind her that you two are more than just partners.

Thank you guys for your answers.
So I'll give you a little update. I took her out few nights ago, didn't tell her anything, until we went to the place we both like, we had fun, later that night we had sex, also we had sex last night as well. It was great.

I think R.C was right, our relationship just got a bit boring, and seems that drop her sex drive..