Power imbalance arguments are nonsense because
existence of power =/= abuse of power
and even if it did (which it obviously doesn’t) we still have no way to measure power. As in the example above. Maybe he was exploiting her, or maybe the other way round. Or maybe no one was exploiting anyone and they were just in love.
We can read tabloids and be judgemental weasels 'till the cows come home and it doesn’t really matter, but if people are claiming that “power dynamics” prove that sex is rape, well now we’re talking about a serious felony. It would be atrocious to put someone in prison based on the absurd bullshit people yap about power imbalances.