I'm not an atturney either, but I play one on the internet, and if I had to prove marital rape I would begin by evidencing
Rape Trauma Syndrome in the wife shortly after the alleged incident. My prosecution strategy would not be a direct accusation of
rape, but an accusation that the husband
caused Rape Trauma Syndrome. Even
consensual sex can cause Rape Trauma Syndrome; a spouse who like it rough takes it to far and/or ignored a safety word, for example.
But even here, I would not be proving
rape, I would be proving a physiological damage. So the question remains: how do you prove it was
rape?