Although we're all here for you shagger, this is too vague for us to help mate,
Was she moaning about the not rotating cos you insist on playing from the rear, was it that you're not able to maintain the solid set up or is it that you can only perform for short stints due to fitness.
Without knowing the answers, in the short term I can only advise that you manage her disappointment levels by stopping the constant demands for 2 up top