I don't believe you when you say she backed down and is just ASS FINGER BANGING you now!
So Elvis has she moved up to doing DP dildos on you yet? Or is she still stretching you out? You two should really go out on the Freak Sex Circuit! There is a lot of money to be made with your expertise of getting Butt Fucked by BIG BLACK SILICON PENISES!
SHE! got bigger boobs and gets to fuck you up your ass. i think you are getting the shorter end of the stick.
(well at least till you being ass fucked my a 7inch dildo.)
Whatever, its not like you havn't thought about in the locker room before. Get in tune with your body. You work it so hard to make it what it is, enjoy it and share it.
Maybe she'd be doing you a favor. A relationship is based on trust and a closeness of mind. Accept that and everything is just the future.
Of course that's just a spotter's opinion. Nice sweats, dude!