Rihanna - Rehab Lyrics Meaning

Well, for me, it's like that 'first' thrill of a love, contract,friendship ...
The rush you get when you feel this is it!! And then, things begin to topple over but oops! You already gave in your all. You went all in and it was all too consuming only to wake up to the realization that the other party was in for a different reason and had one leg in and one out ... Listen;'The only problem is that you was using me in a different way that i was using you' You could say that it's possible her way could have been any way too but then, if it was anything but pure, she wouldn't be lamenting. So, yeah! The other party.